Abstract:
An evaporation apparatus, particularly for forming thin metallization layers on a substrate, comprising a vacuum chamber provided with an inlet opening or port and an outlet opening or port, wherein the vacuum chamber comprises means for transporting at least one substrate from the inlet opening to the outlet opening, at least one evaporation source being provided within the vacuum chamber; the evaporation source is movable inside the vacuum chamber, for directing a jet of vaporized material against the substrate in order to obtain a metallization layer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to an evaporation apparatus particularly adapted to an evaporation plant for manufacturing thin layers on a substrate. More particularly, the invention relates to the evaporation source for a horizontal evaporation plant, to be used in manufacturing photovoltaic solar modules.  
           [0002]    Even more particularly, the present invention relates to an evaporation apparatus for general use in an evaporation or metallization plant for manufacturing thin layers on different substrates.  
           [0003]    As is known, for making photovoltaic modules, and in general for the metallization of substrates, vacuum chambers are generally used, within which the substrate is metallized using an evaporation source.  
           [0004]    However, currently used solutions have the drawback of not being able to apply metallization layers of different widths on the substrate, to obtain a uniform structure of layers and to have passages or transitions between layers with definite gradients.  
           [0005]    Moreover conventional metallization apparatuses are not able to produce surfaces of all sizes and most important, to metallize the whole surface in a single step or pass.  
         SUMMARY OF THE INVENTION  
         [0006]    The aim of the present invention is to eliminate the above-mentioned drawbacks by providing an evaporation apparatus, particularly adapted to manufacture thin layers, which allows the metallization of the whole surface of the substrate to be obtained in a single pass or step.  
           [0007]    Within this aim, a particular object of the present invention is to provide a metallization apparatus which allows to apply, on a single substrate, several layers having different widths.  
           [0008]    Another object of the present invention is to provide a metallization apparatus which allows a uniform structure of the thin layers deposited on the substrate to be obtained.  
           [0009]    Another object of the present invention is to provide a metallization apparatus which allows to obtain passages between one layer and the next with definite gradients.  
           [0010]    Still another object of the present invention is to provide a metallization apparatus which allows to metallize substrates of any size, and comprised of a wide range of materials.  
           [0011]    Not the least object of the present invention is to provide a metallization apparatus which is highly reliable, relatively easy to manufacture and is also competitive from an economical point of view.  
           [0012]    This aim and these and other objects which will become better apparent from the following description are achieved by an evaporation apparatus, particularly for making thin metallization layers on a substrate, comprising: a vacuum chamber provided with an inlet opening and outlet or exit opening, characterized in that said vacuum chamber comprises means for transporting at least one substrate from said inlet opening to said outlet opening, at least one evaporation source being provided within said vacuum chamber, said evaporation source being movable within said vacuum chamber, for directing a jet of vaporized material against said substrate in order to obtain a metallization layer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of the metallization apparatus according to the invention, given only by way of non-limitative example in the accompanying drawings, in which:  
         [0014]    [0014]FIG. 1 is a schematic cross-section view of the metallization apparatus according to the invention; and  
         [0015]    [0015]FIG. 2 is a schematic cross-section view of the structure of an evaporation source used in the apparatus of FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    With reference to the figures, the evaporation apparatus according to the invention, generally designated by the reference numeral  100 , comprises a vacuum chamber  1  provided with a tube  6  for creating a vacuum inside the chamber. The chamber  1  is also provided, at a side thereof, with an inlet opening  4  and, at the opposite side thereof, with an outlet opening or exit  5 , said openings facing a first, pre-heating chamber  2  and a second, cooling chamber  3 , respectively.  
         [0017]    A substrate  8  is then introduced into the chamber  1  through the opening  4 , and moves horizontally through the pre-heating chamber  2  to exit at the outlet  5 , through the cooling chamber  3 .  
         [0018]    The substrate is moved along a number of support and transport rollers  9 .  
         [0019]    Under the support and transport rollers  9 , at least one evaporation source  11  is provided, which can move preferably but not exclusively in a direction opposite that of the substrate  8 .  
         [0020]    Suitably, a plurality of evaporation sources  11  are preferably present, which are arranged to be movable along a closed circuit path, by being supported and transported along an adapted conveyor belt  15 , with a row of evaporation sources  11  always arranged underneath the substrate  8  for the metallization of the substrate itself.  
         [0021]    Suitably, a plurality of rows of evaporation sources  11  can be placed side by side, in order to vaporize (metallize) the width of the substrate  8  as well as the whole length thereof with one pass, that is a single movement of the substrate  8  within the vacuum chamber  1 .  
         [0022]    Above each of the metallization sources reflection means  12  are placed, for directing the jet of evaporation material contained in the evaporation source  11  in the direction of the substrate  8 . The position, the size of an outlet opening  16  of the reflection means, as well as the angle formed by the walls of said reflection means can be any according to requirements.  
         [0023]    The reflection means  12  can be heated.  
         [0024]    In FIG. 1, the arrow indicated by reference number  20  indicates the direction of movement of the substrate  8  inside the vacuum chamber, whereas the arrow indicated by reference number  21  indicates the direction of movement of the evaporation sources  11 , which move in a direction opposite to that of the substrate  8 .  
         [0025]    The evaporation sources  11  can be easily removed from the conveyor belt  15  and the movement of the sources  11  is controlled by a computer and adjusted based on the evaporation material and the layers to be deposited.  
         [0026]    Above the substrate  8  at least one heating source  7  and preferably a number of heating sources  7  are placed, which heat by radiation the substrate  8  and are also controlled by a computer.  
         [0027]    This guarantees the substrate  8  is heated up and kept at the desired temperature.  
         [0028]    The sources  11 , which will be described in detail with reference to FIG. 2, are each periodically supplied with the evaporation material, by means of a passage through an opening  13  from a filling station.  
         [0029]    With reference to FIG. 2, an evaporation source  11  is shown in detail which is comprised of an evaporation container  25  having, in the thickness of the walls thereof, heating means  26  and a mains socket  27  for obtaining the above-mentioned heating.  
         [0030]    Reference number  29  designates the material destined to be vaporized and  28  designates an automatic door which is opened on command on purpose, only for the evaporation process as decided, and most important, when the evaporation source  11  passes by the reflection means  12 .  
         [0031]    With reference to the above-mentioned figures, operation of the apparatus according to the invention, and therefore the method for the use thereof, are as follows.  
         [0032]    The substrate  8 , already pre-heated by the passage through the pre-heating chamber  2 , is supported and carried by rollers  9  and passed through the opening  4  into the vacuum chamber  1 . The substrate  8  is then heated to the desired temperature by means of the heating sources  7  inside the chamber  1 . At the same time the evaporation process takes place and the vaporized material from the evaporation sources  11  is directed—through reflection means  12  placed above the evaporation sources  11 —onto the substrate so as to coat the substrate  8  with a layer having the desired thickness.  
         [0033]    The position and number of the evaporation sources together with their movement in a direction opposite that of the substrate  8  determine the width of the vaporization (metallization) strips which can be obtained on the substrate  8 .  
         [0034]    The temperature at which both the substrate  8  and the evaporation material are heated is adjusted based on the evaporation material itself and the emissions of vapor jet from the evaporation sources  11  can be set in various directions by the movable reflection means  12 . The thickness of the metallization layer deposited on the substrate is checked through the evaporation process and the layer structure can be adjusted at will both on the evaporation material and the evaporation speed. Accordingly, the passages between one layer and the next can be precisely set.  
         [0035]    Therefore, the apparatus and process according to the invention are adapted to produce layers of different materials with definite passages between one layer and the next. This allows, in case determined materials and their compounds are used, such as silicon, copper, gallium, indium, selenium, boron, phosphor, and the like, to produce layers with photovoltaic effect.  
         [0036]    Once the evaporation process is over and therefore all the desired metallizations of the substrate have been obtained on the substrate, the substrate is passed through the exit  5  of the vacuum chamber  1 , and thence to the cooling chamber  3 .  
         [0037]    The evaporation apparatus according to the invention therefore makes it possible to apply metallization layers of different widths, according to the number and position of the evaporation sources, and a uniform structure of the layers to be obtained.  
         [0038]    Additionally, the passages between one layer and the next can be realized with well defined gradients.  
         [0039]    The arrangement of a number of evaporation sources allows to obtain metallizations of any width on a given substrate.  
         [0040]    It has thus been observed that the apparatus and the method according to the invention achieve the intended aim and objects in that thanks to the mobility of the evaporation source or sources, the metallization of a substrate can be obtained with the desired width, thickness and quality.  
         [0041]    The apparatus thus conceived is susceptible of numerous modifications and variations all of which fall within the scope of the inventive concept; all is the details may further be replaced with others technically equivalent.  
         [0042]    In practice, the materials employed as well as the shapes and dimensions may be any according to requirements and to the state of the art.  
         [0043]    The disclosures in German Patent Application No. 100 13 635.4 from which this application claims priority are incorporated herein by reference.