METHOD FOR INSPECTING A CONTAINER AND INSPECTION SYSTEM

Abstract

The present disclosure relates to a method for inspecting a container body adapted and configured to hold substrates, comprising the steps of directing light from a light source onto a reflector element positioned within an interior space of the container body, such that the light is reflected to illuminate at least one interior surface of the container body, wherein the light is reflected by the reflector element in a diffuse manner and generating at least one image of the at least one interior surface by means of at least one camera, and evaluating the state of the container body on the basis of the at least one image.

Claims

1. A method for inspecting a container body configured to hold substrates, the method comprising: directing light from a light source onto a diffuse reflector positioned within an interior space of the container body, such that diffuse reflection light homogenously illuminates at least one interior surface of the container body; with at least one camera, at least one homogenously illuminated image of the at least one interior surface effected by the diffuse reflection light; and evaluating the state of the container body on the basis of the at least one image.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Preferred aspects will now be described referring to the accompanying figures. Herein:

[0030] FIG. 1 shows a schematic top sectional view of an embodiment of the inspection system according to invention, and

[0031] FIG. 2 shows a perspective view of a further embodiment of the inspection system according to the invention.

DETAILED DESCRIPTION

[0032] In FIG. 1, a sectional top view of a preferred aspect of an inspection system according to the disclosure is shown.

[0033] The inspection system, generally designated 10 is adapted to inspect a container body 20 of a container for holding substrates (e.g., wafers or reticles).

[0034] Container body 20 comprises five walls, i.e. two sidewalls 21, 22, a rear wall 23, a bottom wall 24 and a top wall (not shown in the sectional view of FIG. 1). Container body 20 defines an interior space 30 comprising an opening 31.

[0035] By means of a lid member (not shown in FIG. 1), the interior space 30 can be closed and sealed to provide a controlled environment within a substrate container thus provided by container body 20 and the (not shown) lid member.

[0036] The walls of container body 20 each define interior surfaces. The interior surfaces of the walls visible in FIG. 1 are designated 21a - 24a.

[0037] The interior surfaces 21a, 22a of side walls 21, 22 are provided with a number of ridges 32 for holding or stacking substrates. Obviously, in the sectional perspective of FIG. 1, only one of these ridges is visible for each interior surface 21a, 22a.

[0038] Inspection system 10 comprises a light source 100, a reflector element 120 positioned within the interior space 30 of the container body 20, cameras 140 and an evaluating unit 160, provided for example as a computer. Cameras 140 and/or light sources 100 can be provided to be movable in a translational and/or pivotal manner. Guide systems defining translational and pivotal axes may be provided. Such axes are schematically shown and indicated with reference numerals 140a, 140b for cameras 140, and 100c, 100d for the light sources 100. Advantageously, cameras 140 and light sources 100 are mounted on separate guide systems.

[0039] Reflector element 120 comprises two reflection surfaces 122, 124 adapted to provide diffuse reflection of light impinging on it For example, reflection surfaces 122, 124 are provided as diffusors including ground glass diffusors, teflon diffusors or opal glass diffusors.

[0040] Light source 100 comprises at least one light element (e.g., a spotlight element). In the embodiment shown in FIG. 1, two light elements 100a, 100b are provided. In some instances, at least two light elements are used and the light elements can be independently controlled to turn on, turn off, dim, or move individual light elements to change illumination patterns within the container.

[0041] Cameras 140 are provided as line scan cameras, by means of which high resolution images can be generated. Images generated by cameras 140 are passed onto evaluating unit 160 for processing, as will be further explained below.

[0042] Illuminating light 102a, 102b provided by spotlight members 100a, 100b is reflected from reflection surfaces 122, 124 of a reflector element 120 in a diffuse manner, as is schematically shown by dashed lines in FIG. 1. This leads to a homogenous illumination of at least two opposite interior surfaces 21a, 22a of side walls 21, 22. Any shading or shadows, which would occur due to bridges 32 in case of a non-diffuse illumination, can be avoided. Utilizing this homogenous illumination of interior surfaces 21a, 22a, cameras 140 generate images of interior surfaces 21a, 22a, and pass these onto evaluating unit 160.

[0043] The simultaneous illumination of two interior surfaces 21a, 22a opposing one another allows simultaneous generation of images of these surfaces by means of cameras 140. These simultaneously generated images can be simultaneously processed and evaluated by means of evaluating unit 160, resulting in a simultaneous inspection of both interior surfaces 21a, 22a of container body 20.

[0044] On the basis of the images generated by cameras 140, evaluating unit 160 evaluates the state of container body 20. For example, defects on interior surfaces 21a, 22a, especially on ridges 32, can be detected, using appropriate image recognition tools. Also, it is possible to effectively identify contaminations in this way. Also, for example by utilizing comparative reference images, dimensions and measurements of the container body, for example dimensions of the interior surfaces, especially ridges 32, as well as for example incorrectly mounted and/or missing parts can be identified.

[0045] In case rear interior surface 23a is to be inspected, it is possible to remove reflector element 120 from the interior space 30 of container body 20, and for example position a reflector element comprising only one diffusely reflecting surface in interior space 30. According to a further aspect, it is also possible to move reflection surfaces 122, 124 towards one another in an articulated manner, thereby reducing angle α. In case angle α is reduced for example to 0, i.e. the reflection surfaces essentially being arranged back-to-back, cameras 140 can generate sufficiently complete images of rear interior surface 23a.

[0046] According to yet another aspect, it is also possible to move reflection surfaces 122, 124 away from one another in an articulated manner, thereby increasing angle α. In some instances, the reflection surfaces 122 can be inserted into container such that angle α is small, for example, to provide for adequate clearance from container features, and then reflection surfaces 122 can be moved to increase angle α for appropriate illumination of the container surfaces. In some aspects, reflection surfaces 122, 124 can be independently moved relative to each other. Such independent motion need not be limited to changing an angle formed by adjacent surfaces. In some instances, reflection surfaces 122, 124 may be independently moveable relative to one another, for example, in an x and/or y and/or z direction of a Cartesian system.

[0047] FIG. 2 shows a further aspect of an inspection system according to the invention specifically adapted to inspect a FOUP. For ease of reference, identical or equivalent components as already described in connection with FIG. 1 are provided with the same reference numerals.

[0048] As can be seen in FIG. 2, ridges 32 on interior surfaces 21a, 22a are slightly curved, in order to correspond to the shape of typical wafers. In this aspect, reflector element 120 is attached to a platform member 180. By actuating this platform member 180 it is especially easy to insert reflector element 120 into FOUP 20 or remove it therefrom. Alternatively, it is possible to arrange cameras 140 and spotlights 100a, 100b on a separate unit, so that these components can be moved simultaneously in an easy manner. Evaluating unit 160 is not shown in FIG. 2. In other aspects not shown, reflection surfaces 122, 124 may be independenly attached to a platform member having more than one arm for supporting reflection surfaces 122, 124 independently. In other aspects, reflector element 120 may be placed within FOUP 20 so that it stands independenly within the FOUP.

[0049] Be it noted that the inspection system and method, especially the at least one mirror, as described in European patent application EP 17 174 967.4 entitled “Inspection system and method of inspection for substrate containers”, which was filed with the European Patent Office on the same date as the present application, the entire contents of which are hereby incorporated by reference, may be used in conjunction with the method and inspection system for inspecting a container body as described and/or claimed in the present application.

[0050] It should be understood that the foregoing description is only illustrative of the aspects of the disclosed embodiment. Various alternatives and modifications can be devised by those skilled in the art without departing from the aspects of the disclosed aspect Accordingly, the aspects of the disclosed aspect are intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims. Further, the mere fact that different features are recited in mutually different dependent or independent claims does not indicate that a combination of these features cannot be advantageously used, such a combination remaining within the scope of the aspects of the invention.