Abstract:
A ESD-free container is provided. A compound material is used for the creation of the container, the compound material comprising a metallic material that is wedged between layer of polymide material. The compound material is surrounded by layers of PMMA, resulting in a container having a cavity that is surrounded by a first layer of PMMA, a second layer of the compound material and a third layer of PPMA.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method and apparatus for storing and transportation of components, such as reticles, that are used in semiconductor manufacturing. 
     (2) Description of the Prior Art 
     In the art of creating semiconductor devices, it is frequently required to transport these devices from one location in the semiconductor foundry to another location. The same is true for parts of processing tools, such a reticles, which may be required at more than one location. In view of the cost of the parts that are being transported, it is to be expected that extreme care must be taken during transportation, assuring that no damage is incurred by the transported components as a result of the transportation thereof. 
     Components that may need to be transported include the indicated reticles but can also comprise semiconductor (ceramic, glass, gallium arsenide, sapphire and silicon) substrates, surfaces containing epitaxial layers of silicon supported by a base semiconductor, printed circuit boards, flex circuits, metallized substrates, substrates used for flat panel displays and semiconductor device mounting support. 
     When transporting semiconductor components, one of the causes of concern is the occurrence of Electro Static Discharge (ESD) or static electricity, which readily develops on surfaces that contain insulating materials since the insulating materials inhibit the free flow of accumulated electrical charges to other, potentially less harmful locations. Any frictional contact or movement that occurs between components containing insulating materials is prone to result in the accumulation of electromagnetic charges. These electromagnetic charges will, at the time that these charges are brought in contact with a conductive path of low resistivity, discharge, potentially causing damage to the components on the surface of which the ESD has accumulated or injury to an individual through whom the discharge may take place. 
     Strict measures are typically taken to prevent the accumulation of electrical charges by methods of grounding production equipment, by controlling the humidity in the work environment thus preventing the accumulation of electrical charge or by facilitating discharge to ground surfaces by making these surface more conductive and therefore more likely to form a conduit for ongoing electrical discharge during operational activities. As a side benefit of these activities it is typically found that other negative factors in the manufacturing environment, such as the accumulation of dust, is also further controlled and reduced. 
     When however taking into account the size and the complexity of a typical semiconductor manufacturing facility, in addition to the large number of processing tools that are typically present in such a facility, it is to be expected that the occurrence of the accumulation of random electrical charges as yet remains a problem and that the complete elimination of such charges is an objective that as yet has to be met. 
     Since however it remains a requirement that semiconductor components, as listed above, must as yet be transported from location to location within a semiconductor foundry, it is good policy to assume that randomly accumulated electrical charges are present and that therefore the components that are being transported must be protected against potential damage from these charges during transportation. For this purpose a container is frequently used into which the component is posited during transportation. 
     To avoid the above highlighted problems, the container must be constructed such that no electrical charge can affect the component that is loaded into the container. Current containers consist of the body of the container that comprises a top lid, a bottom lid and four sidewalls that extend between the top lid and the bottom lid in a planar perpendicular construction. The top lid, bottom lid and sidewalls define the cavity of the container. The materials that are typically used for the creation of the elements of the container contain electrically insulating materials such as polymeric materials, for reasons that have been detailed above. 
     With this type of a construction it has however been found that, due to the uniform nature of the elements of the container when viewed in cross section of these elements, electrical charge may as yet accumulate on the elements of the container, charging one or more of the elements of the container and therefore as yet penetrating to the component that is contained inside the container. 
     It is therefore of value for the process of transporting semiconductor components in a semiconductor manufacturing environment to provide a container such that no electrical charge can penetrate to the component that is transported inside the container. The invention provides such a container by inserting a metallic coating between layers of polymeric materials, a stack of polymeric material and metallic coating is used to create the elements (such as a top lid, a bottom lid and sidewalls) of the container. 
     U.S. Pat. No. 6,196,391 (Li) and U.S. Pat No. 5,999,397 (Chen et al.) show containers for ESD protection of reticles. 
     U.S. Pat. No. 5,469,963 (Bonora et al.) is a related patent. 
     U.S. Pat. No. 4,776,462 (Ksugi et al.) shows a container for a reticle. 
     SUMMARY OF THE INVENTION 
     A principle objective of the invention is to provide a container that can be used to transport semiconductor components such that these components will not be affected by discharge of static electricity. 
     It is another objective of the invention is to provide a method and package for handling a photolithographic reticle. 
     Another objective of the invention is to provide a method and package that prevents the occurrence of ESD on a photolithographic reticle. 
     In accordance with the objectives of the invention, a new container is provided whereby an article that is stored inside the cavity of a container will not be affected by a discharge of static electricity. The article stored in the container is protected against electromagnetic charges that accumulate as a result of the triboelectricity mechanism and charges that are induced by an electromagnetic field. A compound material is used for the creation of the container, the compound material contains a metallic material that is wedged between layers of polyimide material. The layering of materials effectively shields the component that is loaded into the container against surrounding electromagnetic fields. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a three dimensional view of the component container of the invention. 
     FIG. 2 shows a cross section of the component container of the invention. 
     FIG. 3 shows a cross section of a side surface of the component container of the invention. 
     FIG. 4 shows flow diagram of the steps that are required to create the component container of the invention. 
     FIG. 5 shows additional detail relating to layers of material that are provided for the walls of the component container of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The current method and materials that are used for the creation of a container that is used to transport electrical components is first reviewed. 
     The material that is used for the conventional creation of a container is polymethylmethacrylate (PMMA). The disadvantage that is incurred using this material is that electric charges can accumulate on the container, charging the elements of the container and in this manner penetrating to a component that is positioned inside the container. Electric charges accumulate on insider surfaces of the container, coming in contact with the component that has been placed inside the container, exposing the component to an electromagnetic discharge (ESD). 
     The invention provides for creating a container using layers of material, an outer layer of PMMA is followed by a central layer of metal (such as aluminum) which is followed by an inner coating of PMMA. The construction of the container of the invention is shown three-dimensional view in FIG. 1 the highlights of which are as follows: 
       10 , the component container of the invention 
       12 , the main body of the component container  10  of the invention 
       14 , the (front) access door of the component container  10  of the invention 
       16 , a set of two hinges by which the front access door  14  of the component container  10  of the invention rotates and by means of which the front access door  14  of the component container  10  of the invention is attached to the main body  12  of the component container  10  of the invention 
       18 , knobs or protrusions attached to the front of the access door  14  of the component container  10  of the invention, which motion limited by hinges  16   
       20 , the lower edge or extremity of access door  14 , stretching between point  20 ′ and  20 ″ 
       22 , the upward and rotating motion of edge  20  during the opening of access door  14   
       24 , the front surface of the component container  10  of the invention 
       26 , the back surface of the component container  10  of the invention 
       28 , the left side surface of the component container  10  of the invention when facing the access door  14  of the component container  10  of the invention 
       30 , the right side surface of the component container  10  of the invention when facing the access door  14  of the component container  10  of the invention 
       23 , the bottom surface of the component container  10  of the invention 
       25 , the top surface of the component container  10  of the invention. 
     Above have been listed the main elements of the container  10  of the invention. In order to be able to better define the container of the invention, it is of value to state that the container  10  of the invention has three dimensions. These three dimensions are typically referred to as Cartesian X, Y and Z dimensions (see diagram as part of FIG. 1) that have all the properties of conventional Cartesian X, Y and Z coordinates such as intersecting under an angle of 90 degrees. These Cartesian coordinates of the container of the invention can be defined as intersecting at point  65 , placing the container  10  of the invention above the X-Y plane in a Z-direction. Point  65  is the intersect between the front surface  24 , the bottom surface  23  and the left side surface  28 . Positive directions of the three axis along which the Cartesian coordinates are plotted are the directions that extend along the X-axis from point  65  to the right side surface  30  (the positive direction for the X coordinate), that extend along the Y-axis from point  65  to the back surface  26  (the positive direction for the Y coordinate) and that extend along the Z-axis from point  65  to the top surface  25  (the positive direction for the Z coordinate). 
     The thickness of the surfaces of the component container  10  of the invention, such as front surface  24  and back surface  26 , has not, for reasons of simplicity, been indicated in the three dimensional view shown in FIG.  1 . 
     FIG. 2 shows a cross section of the component container  10  of the invention, taken in a plane that is parallel with the front surface  24  and the back surface  26  of the container  10  of the invention. The exact location of the cross sectional plane is not important as long as this cross sectional plane does not intersect the front surface  24  or the back surface  26  of container  10  of the invention but is located between these two surfaces  24  and  26 . Plane  2 - 2 ′ has been highlighted as one of the planes that can be used for the cross section of FIG. 1 that is shown in FIG.  2 . 
       23 , the bottom surface of the component container of the invention 
       25 , the top surface of the component container  10  of the invention 
       36 , the cavity of the component container  10  of the invention; the components that are transported using the component container  10  of the invention are positioned inside cavity  36   
       38 , the outer layer or shell of the surfaces of the component container  10  of the invention 
       40 , a metallic coating that is embedded within the surfaces of the component container  10  of the invention 
       42 , the inner layer or shell of the surfaces of the component container  10  of the invention 
       44 , first supports which are provided underneath a component support unit  46   
       46 , a plastic component support unit over which the components that are transported using the component container  10  of the invention are positioned during transportation 
       48 , second supports which are provided on the surface of plastic support unit  46 , and 
       50 , the component, preferably a reticle, that has been positioned inside the component container  10  of the invention. 
     Further detail relating to the component container  10  of the invention is shown in FIG. 3, which is a cross section of a side surface of the component container  10  of the invention such as the cross section that is highlighted as cross section  3 - 3 ′ in FIG.  2 . The cross section that is shown in FIG. 3 is not drawn to scale. In an actual construction of the component container  10  of the invention the thickness  54  of layer  40  of metallic coating, preferably containing aluminum, is considerably less than the thicknesses  52  and  56  of respectively layers  42  and  38 . 
     The preferred method for the construction of the component container  10  of the invention is highlighted in the flow diagram of FIG. 4, as follows: 
     1. start with a first container or box that is created using PMMA, this first container (having an outer surface) forms the inner shell  42  of the component container  10  of the invention, this first container is therefore provided with a (front) access door  14 ; step  62 , FIG. 4; it is assumed that the cavity of the first container has been provided with support surfaces such as supports  44  and  48  and surface  46  that are required to position a component, such as a reticle, inside the cavity of the second container; 
     2. provide a metallic surface, preferably containing aluminum, and coat both surfaces of this metallic surface with a layer of polyester; step  64 , FIG. 4 
     3. cover the outer surface of the first container with the polyester coated layer of metallic material, including the access door  14 , creating a first container of PMMA that is surrounded by a (polyester covered) metallic layer; step  66 , FIG. 4 
     4. provide a second container or box that is created using PMMA, this second container (having an inner and an outer surface) forms the outer shell  38  of the component container  10  of the invention, this second container is therefore provided with a (front) access door  14 ; step  68 , FIG. 4, and 
     5. insert the first container (surrounded by the polyester covered metallic layer) inside the second container of PMMA; step  70 , FIG.  4 . 
     The invention can be summarized as follows, in this summarization a close relationship is established between the cross sections of FIGS. 1-3 of the invention and the claims of the invention, as follows: 
     the invention provides a method of creating a component container  10 , shown in three dimensional view in FIG.  1  and in cross section in FIG. 2, for storing and transporting components, such as component  50  shown in FIG. 2, that are used for the manufacturing of semiconductor devices (not highlighted), comprising 
     providing an inner shell  42 , FIGS. 2 and 5, the inner shell comprising polymethylmethacrylate (PMMA), the inner shell having an outer surface  60 , FIG. 5, the inner shell  42  having been provided with a cavity  36 , FIG. 2, the inner shell  42  having been provided with a front surface  24 , FIG. 1, the front surface  24 , FIG. 1, having been provided with a means  14 , FIG. 1, for accessing the cavity  36 , FIG. 2, of the inner shell  42 , the cavity  36 , FIG. 2, having been provided with a means  44 / 46 / 48 , FIG. 2, for positioning the component  50 , FIG. 2 inside the cavity  36 , FIG.  2 . 
     providing a metallic layer  40 , FIGS. 3 and 5, having a first ( 62 , FIG. 5) and a second ( 64 , FIG. 5) surface, the first ( 62 , FIG. 5) and the second ( 64 , FIG. 5) surface having been coated with a layer of polyimide, that is layer  61  of poly having been coating over first surface  62  of layer  40 , FIG. 5, and layer  63  of poly having been coated over second surface  64  of layer  40 , FIG. 5 
     attaching the metallic layer  40  to the outer surface  60 , FIG. 5, of the inner shell, completely covering the inner shell  42  with the metallic layer  40 , creating a two layered shell having a cavity  36 , FIG. 2, the two layered ( 42 / 40 ) shell further having outside surfaces  66 , FIG. 5, the outside surfaces of the two layered shell  42 / 40  having first dimensions in an X, Y and Z direction 
     providing an outer shell  38 , FIGS. 2 and 5, the outer shell comprising polymethylmethacrylate (PMMA), the outer shell  38  having a cavity ( 36 , FIG.  2 ), the outer shell  38  having been provided with a front surface  24 , FIG. 1, the front surface  24  having been provided with a means  14 , FIG. 1, for accessing the cavity  36  of the outer shell  38  further having inside surfaces  68 , FIG. 5, the inside surface  68  of the outer shell  38  having second dimensions in an X, Y and Z direction, the second dimensions of the outer shell  38  being essentially equal to the first dimension of the two layered shell  42 / 40 , thereby completely surrounding the two layered shell  42 / 40  with the outer shell  38   
     the providing the means for positioning the component inside the cavity comprising: 
     (i) providing at least one support post  44 , FIG. 2, having a surface in a plane (not highlighted), the at least one support post  44  comprising a high-resistivity material 
     (ii) providing at least one platform  46 , FIG. 2, and 
     (iii) positioning the at least one platform  46 , FIG. 2, above the at least one support post  44 , FIG. 2, the at least one platform  46  being in contact with the at least one support post  44 , the at least one platform  46  being positioned in the plane of the surface of the at least one support post  44 , the at least one support post  44  comprising a high-resistivity material. 
     Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the spirit of the invention. It is therefore intended to include within the invention all such variations and modifications which fall within the scope of the appended claims and equivalents thereof.