Optics: measuring and testing – Inspection of flaws or impurities – Surface condition
Reexamination Certificate
2002-01-10
2004-01-06
Stafira, Michael P. (Department: 2877)
Optics: measuring and testing
Inspection of flaws or impurities
Surface condition
Reexamination Certificate
active
06674524
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This invention claims priority of the German patent application 101 02 542.4 which is incorporated by reference herein.
FIELD OF THE INVENTION
The invention refers to an arrangement for the visual inspection of substrates, equipped with a microscope for viewing a portion of the substrate located at an inspection point.
BACKGROUND OF THE INVENTION
Arrangements of this kind are used in particular in semiconductor production for the inspection of wafers, in order to examine them for manufacturing defects. An arrangement of this kind is, for example, marketed by the LEICA company under the designation INS 3000. This arrangement, which is depicted schematically in FIG.
7
and
FIG. 8
, comprises a transport device
4
with which wafers having diameters from 100 to 200 mm are delivered to inspection point I. At inspection point I, portions of the wafer to be inspected can be viewed with the aid of a microscope.
A monitor
15
is additionally set up next to the microscope. On this monitor
15
, the viewer is offered a function menu that displays various setting options for the inspection arrangement, for example the type of illumination for a wafer to be inspected, or an opportunity to select an examination region on the wafer. In addition, an image of the wafer presently being examined, or of a portion of that wafer, can be displayed on monitor
15
so that defects on the wafer can also be detected on the basis of the monitor image.
During inspection, an operator sits or stands in front of the microscope and views through its eyepiece
10
the wafer or the portion of interest of that wafer. In this viewing position, which is labeled P
1
in FIG.
7
and
FIG. 8
, the operator can control the operation of the inspection arrangement—for example the advance movement upon transport of a wafer into the inspection position, selection of a region to be examined on the wafer, and the like—by way of the control console present in front of him or her, without changing his or her position. Because of its orientation parallel to eyepieces
10
of the microscope, however, the monitor set up next to the microscope is poorly visible, since its most favorable viewing position P
2
is located right alongside operating position P
1
.
In addition, in inspection arrangements of this kind such as those also known, for example, under the designation “Optistation 7” of the Nikon company, the monitor is arranged too close to the operator. Because of the working distance that must be maintained, in such cases it is possible to use only a relatively small monitor on which details are sometimes difficult to recognize.
SUMMARY OF THE INVENTION
Proceeding from this existing art, it is the object of the invention to develop further an arrangement of the kind cited initially with ergonomics in mind and with the criterion of a compact design.
For that purpose, according to the present invention at least one viewing field for viewing an image or an image area of the substrate, and/or at least one further viewing field for direct viewing of the substrate or a portion of the substrate, is provided next to the microscope viewing port. The microscope viewing port and the viewing fields are arranged with respect to an operating position in such a way that from the operating position, the viewer looks in a first viewing direction perpendicularly onto the microscope viewing port, and in at least one further viewing direction approximately perpendicularly in each case onto one of the viewing fields. In addition, the first viewing direction encloses an acute angle in each case with the further viewing direction or directions.
This allows the operator to work in relaxed and fatigue-free fashion, since it is now possible, from the operating position, to look with a slight inclination or rotation of the head substantially perpendicularly onto the viewing fields present next to the microscope viewing port. The result of this is better identifiability in the region of the viewing fields, as a result of which the error rate during inspection of the wafers can be reduced.
Because of the oblique position of the viewing field with respect to the operating position, the distance between the operating position and the viewing field is moreover increased, so that the latter can be made larger than previously. It is thus possible, for example, to display more operating options or to show a larger image of the portion of the substrate presently being examined.
In a particularly advantageous embodiment of the invention, the arrangement furthermore comprises a housing that surrounds the inspection point of the microscope. The microscope itself is for the most part received in the housing. The viewing field or fields furthermore is or are integrated into one of the outer walls of the housing. This encapsulation not only is attractive in terms of external appearance, but also, principally, allows inspection of the substrates under enhanced cleanliness conditions. For example, an enhanced level of cleanliness can be confined to the interior of the housing. In addition, the encapsulation prevents the risk of operator error or improper actions when positioning the substrates on the inspection point of the microscope. The encapsulation furthermore contributes to workplace safety for the operator.
In a further advantageous embodiment of the invention, a conveying device is additionally provided for transporting the substrates to and away from the inspection point. The control instructions for the conveying device, which is arranged inside the housing, can be entered via the control console.
Furthermore, at least one magazine for receiving the substrates can be integrated into the arrangement, a transfer device for transferring substrates between the magazine and the conveying device additionally being provided. The result is to create a completely closed module for substrate inspection that can be set up, for example, in the vicinity of a wafer production line. Interchangeable magazines are preferably used in this context, thus making possible faster exchange of the substrates to be examined. The magazine or magazines can be configured as separate modules that can be connected to the housing of the inspection arrangement.
For an ergonomically favorable arrangement of the viewing field or fields, it is moreover advantageous if the first viewing direction encloses an angle of less than 50° with the further viewing directions, the operating position being located approximately at the vertex. In practice, angles in the range from 30° to 40° have proven particularly ergonomically favorable.
In a particularly advantageous embodiment, one viewing field is arranged in the horizontal direction on each of the two sides of the microscope viewing port. This thus makes possible, as it were, a panoramic view from the operating position, in which the angle of view is based on operator's natural field of view.
Preferably the two viewing fields are positioned in ergonomically favorable fashion at the same viewing height. In addition, the respective viewing directions toward the viewing fields can enclose identical angles with the first viewing direction, i.e. toward the microscope viewing port. This results in a symmetrical arrangement with respect to the microscope arranged in the middle.
It is not necessary, however, to provide two viewing fields.
A monitor on which an image or image area of the substrate can be visualized is preferably arranged in one viewing field. It is thereby possible to analyze the substrate or a portion thereof with particularly high accuracy. In a particularly simple variant embodiment, this monitor alone serves to provide information about the substrate to be inspected.
It is possible in principle to display on the monitor images of the substrate that are obtained outside the inspection point of the microscope. In a particularly advantageous embodiment of the invention, however, images of the substrate or of parts thereof are generated with the aid of the microscope on the monitor. For tha
Foley & Lardner
Leica Microsystems Jena GmbH
Stafira Michael P.
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