JP4222709B2 - Work surface inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a workpiece surface inspection apparatus for inspecting the surface of a workpiece such as a glass substrate, and more particularly to a workpiece surface inspection apparatus that can inspect the surface of a workpiece with high accuracy.
[0002]
[Prior art]
Conventionally, an inspection method as shown in FIG. 3 is known as a workpiece surface inspection method. That is, the work 2 to be inspected is placed on the mounting table 5 having high flatness through the solution, and the surface inspection is performed by the laser interferometer 4 or the like with the inspection surface of the work 2 facing upward. In this case, the index matching liquid 3 is used as the solution, and the index matching liquid 3 has the same refractive index as that of the workpiece 2 or an extremely close refractive index. The light from the laser interferometer 4 is reflected only on the inspection surface of the workpiece 2, and this reflected light enters the laser interferometer 4 to inspect the surface shape of the workpiece 2. On the other hand, the light that has entered the workpiece 2 is transmitted from the bottom surface of the workpiece 2 through the index matching liquid 3 to the mounting table 5 side and absorbed.
[0003]
[Problems to be solved by the invention]
In the inspection method described above, the amount of the solution interposed between the workpiece 2 and the mounting table 5 affects the distortion of the workpiece 2, and the tendency becomes stronger as the workpiece 2 becomes larger.
[0004]
That is, as the amount of the solution 3 is smaller, the work 2 has a higher contact force with the lower mounting table 5 and is distorted, and the influence of the flatness of the lower mounting table 5 increases. Therefore, when the amount of the solution 3 is sufficiently increased and the workpiece 2 is brought into a floating state, the influence of the mounting table 5 is reduced. However, with the passage of time, the amount of the solution 3 between the workpiece 2 and the mounting table 5 decreases, and the adhesion force changes accordingly, and the workpiece 2 is distorted by the influence of the flatness of the mounting table 5. Therefore, the surface inspection of the workpiece 2 cannot be performed with high accuracy.
[0005]
The present invention has been made in consideration of such points, and an object thereof is to provide a workpiece surface inspection apparatus that can always inspect the surface of a workpiece with high accuracy without being affected by time.
[0006]
[Means for Solving the Problems]
The present invention provides a workpiece mounting table having a black mounting surface for mounting a workpiece via an index matching liquid, and a workpiece mounting table provided above the workpiece mounting table. The workpiece is irradiated with light and reflected from the workpiece. An interferometer that detects the flatness of the workpiece surface, and a plurality of discharge holes are provided on the mounting surface of the workpiece mounting table, and a liquid supply device that supplies an index matching liquid is connected to the discharge holes. It is a workpiece surface inspection device.
[0007]
According to the present invention, the index matching liquid is supplied to the discharge hole by the liquid supply device, and the index matching liquid is discharged from the discharge hole onto the mounting surface. The workpiece on the placement surface floats from the placement surface by the index matching liquid from the discharge hole. During this time, the work is irradiated with light from the interferometer, and the flatness of the surface of the work is inspected by the interferometer based on the reflected light from the work.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
1 and 2 are views showing an embodiment of a workpiece surface inspection apparatus according to the present invention.
[0010]
As shown in FIGS. 1 and 2, a workpiece surface inspection apparatus 10 is provided on a workpiece mounting table 5 having a mounting surface 5 a on which a rectangular glass workpiece 2 is mounted, and above the workpiece mounting table 5. And a laser interferometer 4 such as a Fizeau interferometer, for example, which inspects the flatness of the surface of the work 2 by irradiating light onto the work 2 and detecting reflected light from the work 2.
[0011]
Among these, the mounting surface 5a of the workpiece mounting table 5 has a square shape and black color so as to absorb light. In addition, a plurality of discharge holes 6 are provided in the mounting surface 5a of the work mounting table 5 over the entire mounting surface 5a. Further, a liquid supply device that includes the filter 11 and the pump 12 and supplies the index matching liquid 3 is connected to the discharge hole 6.
[0012]
That is, a liquid storage groove 8 is provided on the periphery of the mounting surface 5 a of the workpiece mounting table 5, and a filter 11 and a pump 12 are connected to the liquid storage groove 8 via a pipe 13. The pipe 13 is connected to the discharge hole 6 of the work table 5 so that the index matching liquid 3 flowing through the pipe 13 is discharged from the discharge hole 6.
[0013]
The placement surface 5a is provided with four stoppers 7 that restrict the movement of the workpiece 2 in the horizontal direction.
[0014]
Next, the material and shape of each component will be described. 1 and 2, the workpiece mounting table 5 is made of aluminum, and at least the mounting surface 5a of the workpiece mounting table 5 is subjected to black alumite treatment, thereby becoming black. Further, the discharge holes 6 of the mounting surface 5a are arranged at a pitch of 3 mm, and each has a diameter of 0.5 mm.
[0015]
Next, the operation of the present embodiment having such a configuration will be described. As a work 2 to be inspected, a work (1737 glass: manufactured by Corning, 150 × 150 mm, thickness 1 mm, refractive index 1.52) is used. A laser interferometer (Fizeau interference light) 4 having a semiconductor laser is used to inspect the flatness of the workpiece 2 surface. When inspecting the flatness of the workpiece 2, it is desirable that the workpiece 2 can be measured in a natural state without distortion.
[0016]
According to the present invention, the distortion of the workpiece 2 is extremely small, and the surface inspection of the workpiece 2 can be performed in a more natural state, and is not affected by the flatness of the mounting table 5 as in the prior art.
[0017]
That is, first, the work 2 is placed on the placing surface 5a of the work placing table 5 which is made of aluminum black anodized. On the mounting surface 5a, discharge holes 6 having a diameter of 0.5 mm are formed almost everywhere at a pitch of 3 mm. Next, when the pump 12 is operated, the transparent index matching liquid 3 (xylene: refractive index 1.50) is sent from the pipe 13 to the discharge hole 6 of the mounting surface 5a, and the index matching liquid 3 is stained from the discharge hole 6. It is discharged onto the mounting surface 5a so as to be released.
[0018]
In this case, the workpiece 2 floats from the placement surface 5a, and the adhesion between the workpiece 2 and the placement surface 5a is lost. When the workpiece 2 floats, the unevenness on the back surface of the workpiece 2 is absorbed by the layer of the index matching liquid 3, and no force is applied to a specific portion of the workpiece 2.
[0019]
By the way, if the diameter of the discharge hole 6 is large and the number of the discharge holes 6 is small, the discharge amount discharged from each discharge hole 6 increases, and the variation in the discharge amount from each discharge hole 6 becomes a problem. Therefore, it is desirable that the diameter of the discharge holes 6 is as small as possible and the number of the discharge holes 6 is large.
[0020]
Further, the floating work 2 is prevented from moving in the horizontal direction by the stopper 7.
The index matching liquid 3 discharged onto the mounting surface 5a of the workpiece mounting table 5 is then sent from the liquid storage groove 8 to the filter 11 via the pipe 13. The index matching liquid 3 is purified by the filter 11 on the inlet side of the pump 12 and then sent to the pump 12.
[0021]
During this time, laser light is irradiated from the laser interferometer 4 toward the surface of the work 2, and reflected light from the surface of the work 2 enters the laser interferometer 4. In this way, the flatness of the surface of the workpiece 2 can be inspected by the laser interferometer 4.
[0022]
Further, the laser beam that has passed through the workpiece 2 passes through the index matching liquid 3 having substantially the same refractive index as that of the workpiece 2 and enters the mounting surface 5a side. In this case, since the mounting surface 5a is black anodized, the laser light is not reflected on the mounting surface 5a and is absorbed by the mounting surface 5a.
[0023]
For this reason, since only the reflected light on the surface of the workpiece 2 is incident on the laser interferometer 4, the flatness of the surface of the workpiece 2 can be inspected with high accuracy. Further, since the workpiece 2 is always kept floating from the placement surface 5a by the index matching liquid discharged from the discharge hole 6 of the placement surface 5a, the workpiece 2 comes into close contact with the placement surface 5a during the surface inspection. There is nothing. For this reason, the surface inspection of the workpiece 2 can be accurately performed without being affected by the flatness of the mounting surface 5a.
[0024]
【The invention's effect】
As described above, according to the present invention, the workpiece constantly floats on the placement surface by the index matching liquid discharged from the discharge hole on the placement surface. For this reason, even if time passes, a workpiece | work does not contact | adhere to a mounting surface, and it can always measure the flatness of a workpiece | work surface accurately with no influence of the flatness of a mounting surface.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of a workpiece surface inspection apparatus according to the present invention.
FIG. 2 is a side view of the workpiece surface inspection apparatus.
FIG. 3 is a diagram showing a conventional workpiece surface inspection apparatus.
[Explanation of symbols]
2 Work 3 Index matching liquid 4 Laser interferometer 5 Work placement table 5a Placement surface 6 Release hole 7 Stopper 8 Liquid storage groove 10 Work surface inspection device 11 Filter 12 Pump

Claims (4)

A workpiece mounting table having a black mounting surface for mounting the workpiece via an index matching liquid;
An interferometer that is provided above the workpiece mounting table and irradiates the workpiece with light and detects the flatness of the workpiece surface by reflected light from the workpiece;
A work surface inspection apparatus, wherein a plurality of discharge holes are provided on a mounting surface of a work mounting table, and a liquid supply device for supplying an index matching liquid is connected to the discharge holes. The work surface inspection apparatus according to claim 1, wherein the liquid supply apparatus includes a pump for supplying an index matching liquid. 3. The workpiece surface inspection apparatus according to claim 2, wherein a liquid storage groove is provided on the periphery of the mounting surface of the workpiece mounting table, and the liquid storage groove is connected to the inlet side of the pump via a filter. The workpiece surface inspection apparatus according to claim 1, wherein a stopper for restricting horizontal movement of the workpiece is provided on the workpiece mounting table.

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