U.S. patent application number 12/741110 was filed with the patent office on 2012-12-27 for inspection device.
This patent application is currently assigned to Zimmermann & Schilp Handhabungstechnik GmbH. Invention is credited to Michael Schilp, Josef Zimmermann, Adolf Zitzmann.
Application Number | 20120327402 12/741110 |
Document ID | / |
Family ID | 40530440 |
Filed Date | 2012-12-27 |
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United States Patent
Application |
20120327402 |
Kind Code |
A1 |
Schilp; Michael ; et
al. |
December 27, 2012 |
INSPECTION DEVICE
Abstract
The invention relates to a device for inspecting
contact-sensitive planar materials or workpieces, e.g. wafers for
the semiconductor industry, solar cells, glasses, FPD substrates,
or biologically active substrates for biosensors, as well as
materials having contact-sensitive curved surfaces. Said inspection
device comprises a support element (1) for supporting a material
(3) on the top face of the support element (1), at least one
oscillator which is connected to the support element (1) and the
oscillation frequency and amplitude of which are selected in such a
way as to keep the material (3) hovering on the support element
(1), and at least one optical sensor (4). The support element is
made of a light-permeable material, and the optical sensor (4) is
arranged below the support element (1).
Inventors: |
Schilp; Michael;
(Regensburg, DE) ; Zimmermann; Josef; (Regensburg,
DE) ; Zitzmann; Adolf; (Teunz, DE) |
Assignee: |
Zimmermann & Schilp
Handhabungstechnik GmbH
Regensburg
DE
|
Family ID: |
40530440 |
Appl. No.: |
12/741110 |
Filed: |
October 31, 2008 |
PCT Filed: |
October 31, 2008 |
PCT NO: |
PCT/DE2008/001790 |
371 Date: |
December 21, 2010 |
Current U.S.
Class: |
356/237.2 |
Current CPC
Class: |
G01N 21/01 20130101;
G01N 21/88 20130101; G01N 21/94 20130101; G01N 2021/0339 20130101;
G01N 21/9501 20130101; G01N 21/8806 20130101 |
Class at
Publication: |
356/237.2 |
International
Class: |
G01N 21/88 20060101
G01N021/88 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 2007 |
DE |
10 2007 052 530.5 |
Claims
1. Inspection device which comprises: a support element (1) for
supporting a material (3) on the top side of the support element
(1), at least one oscillator connected to the support element (1),
wherein the oscillation frequency and amplitude of the oscillator
are selected so as to keep the material (3) levitating on the
support element (1), and at least one optical sensor, wherein the
support element (1) is made of a light-permeable material and the
optical sensor is arranged below the support element (1).
2. Inspection device according to claim 1, characterized in that
the support element (1) is made of glass.
3. Inspection device according to claim 1, characterized in that
the support element (1) is made of a light-permeable ceramic
material.
4. Inspection device according to claim 1, characterized in that
the support element (1) is made of an oscillatory light-permeable
plastic material.
5. Transport and inspection device for materials which are to be
transported and inspected and are moved along a transport path by
using transport means, characterized in that an inspection device
according to any of the claims 1 to 4 is arranged within the area
of the transport path.
Description
[0001] The invention relates to a device for inspecting
contact-sensitive planar materials or work-pieces, e.g. wafers for
the semiconductor industry, solar cells, glasses, FPD substrates,
or biologically active substrates for biosensors, as well as
materials having contact-sensitive curved surfaces. In the
following, every kind of material or work-piece will be denoted as
material. The surfaces of materials will be treated in different
working steps, wherein treatment shall be understood to be working
steps like vapor-deposition or structuring, for example.
Afterwards, the result of treatment will be inspected. Inspection
can be carried out by using a camera provided with an image
recognition and evaluation program.
[0002] Technologies assigned for the treatment of the top surface
and also of the bottom surface of the materials require both these
surfaces to be inspected. The top surface of material can be
inspected easily, as the material is positioned on an inspection
table or a conveyer belt so that there is a free view onto the top
surface thereof. However, it is very difficult to inspect the
bottom surface of material at the same time, as this surface is at
least partly covered by sections of the support structure so that
e.g. a camera is not capable of scanning all of this surface.
[0003] For example, when a solar cell the bottom surface thereof
being very sensitive to mechanical contact is transported, this
solar cell is borne by several small conveyer belts. Therefore,
only those areas of the bottom surface of the solar cell, which are
not covered by the conveyer belts, can be inspected by a camera
from below. However, when the total bottom surface of the solar
cell is to be inspected, the solar cell must be removed from the
conveyer belt, turned and again put onto the conveyer belt, but
this is time-consuming and susceptible to trouble with continuously
running processes.
[0004] In order to solve these problems, according to the prior
art, the transport path is subdivided into several segments
separated from each other by gaps so that the material is delivered
up by the single segments. As the material is not supported at the
transfer gap, the total width thereof can be scanned. However, when
the material to be transported is insufficiently stiff, there is
the problem that the transfer gap has to be dimensioned very small.
Now and then, it is not possible to perform scanning in an
unhindered way.
[0005] Therefore, it is an object of the invention to provide a
technology for transporting contact-sensitive materials along a
transport path and optically inspecting the bottom surfaces thereof
totally without hindering the inspection to be carried out at those
positions where the material is supported and thus, is covered.
[0006] This object is solved by an inspection device according to
claim 1 and a transport and inspection device according to claim
5.
[0007] The invention according to claim 1 relates to an inspection
device which comprises a support element for supporting a material
to be inspected. An oscillator is connected to the support element
to cause it to vibrate, wherein the oscillation frequency and the
amplitude of which are selected so as to keep the material to be
inspected hovering on the top side of the support element by
ultrasonic levitation. The top surface of the support element is
matched to the geometric shape of the bottom surface of the
material.
[0008] According to the invention, the support element is made of a
light-permeable material to allow the bottom surface of the
material levitating on the support element to be scanned optically,
that is, to be inspected by means of an optical sensor such as a
camera, an interferometer, a Speckle measuring instrument or a line
scan camera.
[0009] In this way, it is possible to keep contact-sensitive
materials such as wafers or solar cells levitating during an
inspection and to inspect the bottom surfaces thereof
completely.
[0010] Depending on the light used for the inspection, it may be
expedient to make the support element of a material such as glass,
light-permeable ceramic material, sapphire or oscillatory
light-permeable plastic material, as defined in claims 2 to 4.
[0011] It will be obvious to those skilled in the art that the
optical properties of the support element are dependent on the
material which it is made of, on the geometric shape thereof and on
the wave length of the light used for the inspection.
[0012] To transport wafers, for example, the support element is
formed as a plane-parallel plate having an even surface. When
optical systems have to be constructed, an expert skilled in the
art will design the optical sensor thereof so that the optical
properties of the plane-parallel plate with respect to the
refraction of light are considered.
[0013] On the other hand, when rod-like material having a circular
cross section is to be held in a non-contact way and to be
inspected, the rod-like material is located in a semi-circular
groove of the support element, the radius thereof corresponding to
that of the rod-like material. In this case, the optical properties
of the support element are different from those of a plane-parallel
plate and, therefore, the refraction and reflection properties of
curved surfaces have to be considered by those skilled in the art,
which is true for designing the optical sensor and also for
designing the illuminating system required.
[0014] Thus, the support element has to be regarded as a structural
optic element which can be made by using technologies known for
making and coating structural optic elements.
[0015] According to claim 5, a transport and inspection device is
provided, on which materials are transported along a transport
path. An inspection device according to any of the claims 1 to 4 is
arranged at a certain position of the transport path.
[0016] As the support plate is dependent on the shape and size of
the material to be supported and the surface to be inspected may be
the total surface of the material or only a section thereof, it is
not possible to give concrete geometric information as to the
design and shape of the support plate. It is obvious to those
skilled in the art and knowing the disclosed technical science that
only that surface section of the support plate, in which the
propagation of light beams is not shadowed or disturbed, can be
used for the inspection.
[0017] It is obvious to those skilled in the art, in which way the
signals provided by an optical sensor have to be evaluated. As
signal processing and evaluating is not subject-matter of the
invention but known from the prior art, it is not necessary to
explain it in detail for those skilled in the art.
[0018] Below, the invention will be explained in detail by means of
an embodiment and the enclosed schematic drawings.
[0019] FIG. 1 is a schematic and perspective view of a support
plate with a planar material put on it.
[0020] FIG. 2 is a side view of the support plate shown in FIG. 1
and a camera arranged below it.
[0021] FIG. 1 is a schematic and perspective view of a support
plate 1 that is bent laterally. An oscillator (not shown) is
connected to the leg 2 of this plate. Generation of oscillation is
indicated by a double arrow. The planar material 3 is a silicon
wafer levitating 0.1 mm above the support plate 1.
[0022] FIG. 2 is a side view of the structure shown in FIG. 1. A
camera 4 is arranged below the support plate 1, which is used for
inspecting the bottom surface of the silicon wafer levitating on
the support plate. The support plate is made of an optical glass
and is laterally illuminated from below.
* * * * *