JPH0449046B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flatness measuring device that measures the flatness of the surface of a thin plate-shaped object to be measured, and particularly relates to a flatness measuring device that measures the flatness of the surface of a thin plate-shaped object to be measured. The present invention relates to a flatness measuring device as described above.

[Prior Art] For example, in the intermediate inspection process and final inspection process of the manufacturing process of semiconductor wafers and ceramic substrates used as materials for manufacturing IC semiconductor circuit elements, magnetic disks and optical disks as storage media for computers, etc. A flatness measuring device is one of the devices for inspecting whether these products are manufactured to standard dimensions.

This flatness measuring device mainly measures the undulation phenomenon (undulation phenomenon) on the surface of a thin plate-like object to be measured, such as the wafer. Generally, such a flatness measuring device is constructed as shown in FIG.
That is, a rail 2 is disposed on a frame 1 in a housing (not shown), and the rail 2 has an L-shaped cross section through two linear bearing bodies 3a, 3b shown in FIG. Platform 4 is engaged. Note that this measuring table 4 is moved in the direction in which the rail 2 is laid by a feeding mechanism (not shown) such as a ball screw.

For example, a circular object to be measured 6 is placed on the upper surface 5 of the measurement table 4 . A support arm 7 whose upper end is fixed to the ceiling of the casing is disposed above the measuring table 4 to face it, and a distance measuring sensor 8 is attached to the lower end of the support arm 7.

As shown in FIG. 9, within this distance measurement sensor 8, a light source 9 such as a light emitting diode that outputs measurement light of a single wavelength, and a position sensor 10 that can detect the light receiving position are installed at a predetermined angle. It is located with a

In the flatness measuring device configured in this manner, when the measuring table 4 is moved along the rail 2, the position of the distance measuring sensor 8 facing the object to be measured 6 is sequentially moved. Then, at any position on the measuring table 4, the measuring light 11 output from the light source 9
is reflected by the surface of the object to be measured 6 and is input to the position sensor 10 as shown by the solid line. The position sensor 10 outputs a position signal corresponding to the incident position of the measurement light 11. Next, when the measuring table 4 moves and the surface position of the object to be measured 6 changes, for example, as shown by the two-dot chain line, the incident position of the measuring light 11 on the position sensor 10 changes. Therefore, the change in distance between the distance measurement sensor 8 and the object to be measured 6, that is, the undulation phenomenon on the surface of the object to be measured 6 can be measured.

[Problems to be Solved by the Invention] However, the flatness measuring device configured as described above also has the following problems. That is, as shown in FIGS. 7 and 8, in order to measure the undulation phenomenon of each part of the object to be measured 6, the distance measurement sensor 8 is kept fixed;
An object to be measured 6 mounted on a measuring table 4 is moved. Although the measuring table 4 is moved along the rail 2 by precisely configured linear bearing bodies 3a and 3b, it is impossible to control vibrations accompanying the movement to zero. The measuring table 4 therefore vibrates in various vibration modes during the movement. For example, as one vibration mode, pitting vibration as shown by arrow B occurs around center point A of measuring table 4 as shown in FIG. Therefore, in this case, the object to be measured 6 at a position near the center point A of the upper surface 5 of the measuring table 4
Although the vertical position of the surface does not change much, the vertical position of the surface of the object to be measured 6 located at both ends varies greatly. As a result, there is a large difference in the measured value between when the distance measurement sensor 8 is located at the center position shown as a in the figure and when it is located at the peripheral positions shown as b and c in the figure, making it difficult to obtain accurate measurement results. There is a problem that cannot be resolved.

In particular, when measuring objects to be measured such as wafers and ceramic substrates as described above, the thickness of the objects to be measured is approximately 0.2 to 0.6 mm, and the outer diameter is approximately 75 to 75 mm.
150mm is also available. Since such a shape requires a measurement accuracy of about 1 micron, it has been difficult to maintain this measurement accuracy when the above-mentioned vibration phenomenon occurs.

Furthermore, as described above, since the object to be measured 6 is very thin, there is also a concern that it may shift horizontally on the measuring table 4 due to vibration.

The present invention has been made in view of the above circumstances, and its purpose is to minimize measurement errors caused by vibration by moving a distance measurement sensor without moving the object to be measured. I can,
An object of the present invention is to provide a flatness measuring device that can significantly improve measurement accuracy.

[Means for Solving the Problems] The flatness measuring device of the present invention includes a measuring table on which a thin plate-shaped object to be measured is placed;
A rotation support mechanism that supports this measurement table so that its top surface rotates within a horizontal plane, and a pair of rotating support mechanisms that are parallel to the top surface of the measurement table, spaced apart from each other in the vertical direction, and parallel to the measurement direction of the object to be measured. A rail, a plurality of linear bearing bodies that engage at different positions in the rail laying direction on each rail and are movable in the rail laying direction, one end of which is fixed to the plurality of linear bearing bodies, and the other An L-shaped measuring arm whose end is above the measuring stand and located at the center between each linear bearing body in the rail installation direction, and a measuring arm connected to each rail via each linear bearing body are connected to the measuring stand. A moving mechanism that moves the object to be measured placed on the object in the measurement direction, and a distance mechanism that is attached to the other end of the measuring arm and that measures the change in distance to the object during the movement period without contact. A measurement sensor is provided.

[Operation] In the flatness measuring device configured as described above, one end of the measuring arm, to which the distance measuring sensor is attached to the other end, is engaged with the rail via the linear bearing body. This rail is laid parallel to the top surface of the measuring table on which the object to be measured is placed and parallel to the measuring direction of the object to be measured, so if the measuring arm is moved by the moving mechanism, it can be attached to the measuring arm. The distance measurement sensor moves in the measurement direction above the object to be measured. In this case, the measurement arm is attached to a plurality of linear bearing bodies that engage with each rail of a pair of rails that are laid parallel to the top surface of the measurement table and spaced apart in the vertical direction.
Therefore, since the measuring arm is engaged with a pair of rails spaced apart in the vertical direction, pitting vibration, in which both ends of the measuring arm in the moving direction vibrate in the vertical direction, is less likely to occur when the measuring arm moves. Further, the position in the measurement direction of the other end (upper end) of the measurement arm to which the distance measurement sensor is attached coincides with the center position between the linear bearing bodies. Therefore, even if pitching vibration occurs due to the movement of the measurement arm, there is almost no change in the position of the distance measurement sensor, so measurement errors due to vibration are reduced. Furthermore, since the measuring table does not move, the object to be measured does not vibrate.

[Example] An example of the present invention will be described below with reference to the drawings.

FIG. 2 is a front view showing the entire flatness measuring device of the embodiment. As shown in the figure, this device processes analog signals from a flatness measuring device main body 21, a drive control device 25 that drives and controls a measuring arm 32 of the flatness measuring device main body 21, and a circular measuring table 24, and a distance measuring sensor 36. A personal computer 26 performs arithmetic processing on each measurement result, and a CRT display tube 27 displays the arithmetic and analysis results.

Figure 3 shows the flatness measuring machine body 21 of the embodiment.
FIG. 1 is a perspective view showing the appearance of the
FIG. 3 is a cross-sectional view taken along the −X′ line. The circular measuring stand 24 is attached to the upper surface of the case 28 which is formed into a substantially rectangular parallelepiped shape.
A boss 30 is attached to the center of the upper surface 29 of the sensor 4 for placing an annular object to be measured such as a magnetic disk or an optical disk. Note that the boss 30 is removed when placing an object to be measured in which no holes are formed, such as a wafer or a ceramic substrate. This measuring table 24 is rotationally controlled to an arbitrary angular position by a servo motor 31 placed in a case 28 .

Furthermore, a rectangular window 33 is bored in the upper surface of the case 28 through which a measuring arm 32 formed in a substantially L-shape moves back and forth. Five metal round bars 34 parallel to the moving direction of the measuring arm 32 are fitted into the rectangular window 33 in a horizontal row.

A distance measuring sensor 36 is attached to the distal end of the L-shaped measuring arm 32 located above the upper surface of the case 28 so as to face downward via a vertical adjustment device 35. A light source 36a that outputs measurement light and a position sensor 36b that receives measurement light reflected from the surface of the object to be measured are attached to the tip of the distance measurement sensor 36. Then, when the measuring arm 32 is moved, the distance measuring sensor 36
The dimensions of the measuring arm 32 are set so that the center of measurement passes through the center line of the measuring table 24.
A through hole 37 through which the five round bars 34 pass is provided at a position facing the square window 33 of the measurement arm 32.
is drilled. Further, on a partition wall 38 provided in the case 32, two rails 39 and 40 are provided which are parallel to the upper surface 29 of the measuring table 24 and parallel to the measurement direction of the object to be measured placed on this upper surface 29. installed. The rails 39, 40 have two linear bearing bodies 41a, 41b and 42, respectively, which engage with the rails 39, 40, respectively.
a, 42b are provided, and these linear bearing bodies 41a, 41b and 42a, 42b are fixed to one side of the measuring arm 32 located inside the case 28. The linear bearing bodies 41a, 41
For example, as shown in FIG. 4, b engages with the rail 39 and is configured to be able to move freely in the direction in which the rail 39 is laid.

Furthermore, a ball screw 43 as shown in FIG. The measuring arm 32 is penetrated through the measuring arm 32 through the measuring arm 32 . This ball screw 43 is rotated by a feed motor 46 via a belt 45. Therefore, when the feed motor 46 is rotated, the measuring arm 32 having the distance measuring sensor 36 attached to its tip moves in the measuring direction. Therefore, the ball screw 43 and the nut 4
4. The belt 45 and the feed motor 46 constitute a moving mechanism that moves the measuring arm 32 in the measuring direction of the object to be measured.

In the flatness measuring device configured as described above, the feed motor 46 is first started to move the measuring arm 32 to either end of the rectangular window 33. The next object to be measured is placed on the upper surface 2 of the circular measuring table 24. Then, the measuring table 24 is rotated by the servo motor 31 to align the direction in which the measurement target object is to be measured with the moving direction of the distance measuring sensor 36. Next, the distance measurement sensor 36 is moved onto the measurement table 24, and the vertical position adjuster 35 is used to measure the distance so that the measurement light reflected from the surface of the object to be measured is incident on the approximately central position of the position sensor 36b. Adjust the vertical position of the sensor 36. When the adjustment is completed, the distance measurement sensor 36 is moved again to the movement start position at one end of the rectangular window 33. After the above initial setting operation is completed, the feed motor 4
6, the distance measuring sensor 36 attached to the tip of the measuring arm 32 moves at a constant speed in the measurement direction above the object to be measured. Thus, the distance measuring sensor 36 measures the undulation phenomenon of the object to be measured using the measurement principle described above. The measurement results are processed by the personal computer 26.
It is displayed on the CRT display tube 27.

The vibration phenomenon during the period of movement of the measuring arm 32 of the flatness measuring device constructed in this way will be explained using FIG. 6. In this case, the measuring table 24
is stopped during the measurement period, so this measurement platform 2
No vibration occurs due to 4. The measuring arm 32 has linear bearing bodies 41a, 41b, 42a, 42b on two rails 39, 40, respectively, as shown in the figure.
But he is guided. Therefore, as shown in FIG.
9 and 40, pitting vibration is less likely to occur compared to the conventional device that engages only at two horizontal locations as shown in FIG. Further, even if pitching vibration shown by arrow D centered on point C, which is the center position, occurs in the moving direction as shown in FIG. Since the vibration passes through point C, which is the center of vibration, there is almost no vertical positional change in the lower end position of the distance measurement sensor 36. Therefore, the light source 36a attached to the lower end of the distance measurement sensor 36, the position sensor 36b and the measurement table 2
Even if pitching vibration occurs, the distance between the measured object 47 and the measured object 47 placed on the test piece 4 hardly changes. As a result, measurement accuracy can be significantly improved.

Further, since the measurement table 24 does not move during the measurement period, even if the object to be measured is extremely thin, such as a wafer or a ceramic substrate, the object to be measured will not move due to vibration during the measurement period.

Note that the present invention is not limited to the embodiments described above. In the embodiments, two rails and four linear bearing bodies were provided, but the number of these rails installed may be changed as necessary. It's okay.

[Effects of the Invention] As explained above, according to the present invention, during the measurement period, the distance measurement sensor is moved without moving the object to be measured. Furthermore, the measurement arm is attached to a plurality of linear bearing bodies that respectively engage with each rail of a pair of rails laid parallel to the top surface of the measurement table and spaced apart from each other in the vertical direction. Therefore, since the measuring arm is engaged with a pair of rails spaced apart in the vertical direction, pitting vibration, in which both ends of the measuring arm in the moving direction vibrate in the vertical direction, is less likely to occur when the measuring arm moves. Further, the position of the other end of the measurement arm to which the distance measurement sensor is attached in the measurement direction coincides with the center position between the linear bearing bodies. Therefore, measurement errors due to vibration can be suppressed to a minimum, and measurement accuracy can be greatly improved.

[Brief explanation of the drawing]

1 to 6 show a flatness measuring device according to an embodiment of the present invention, FIG. 1 is a sectional view showing the main parts, FIG. 2 is a front view showing the entire device, and FIG. 3 is a flatness measuring device according to an embodiment of the present invention. 4 is a perspective view showing the rail and linear bearing body taken out, FIG. 5 is a front view showing the moving mechanism taken out, and FIG. 6 is a schematic diagram showing the vibration state. Fig. 7 is a perspective view showing the main parts of a conventional flatness measuring device, Fig. 8 is a schematic diagram showing the vibration state of the conventional flatness measuring device, and Fig. 9 is a schematic diagram for explaining the measurement principle of a distance measuring sensor. It is a diagram. 21...Flatness measuring device main body, 24...Measurement stand, 28...Case, 29...Top surface, 31...
Servo motor, 32...Measuring arm, 33...Square window, 34...Round bar, 36...Distance measurement sensor,
37...Through hole, 39, 40...Rail, 41
a, 41b, 42a, 42b... linear bearing body,
43... Ball screw, 44... Nut, 46...
Feed motor, 47...Object to be measured.

Claims (1)

[Claims] 1. A measuring table 24 on which a thin plate-shaped object to be measured is placed, a rotation support mechanism 31 that supports this measuring table so that the upper surface rotates in a horizontal plane, and a rotating support mechanism 31 that is parallel to the upper surface of the measuring table and that is parallel to the upper surface of the measuring table. A pair of rails 39 and 40 are spaced apart from each other in the vertical direction and are further laid parallel to the measurement direction of the object to be measured, and the rails are engaged at mutually different positions in the rail laying direction on each rail, and the rails are engaged in the laying direction of each rail. A plurality of linear bearing bodies 41a, 41 movably provided in
b, 42a, 42b, and an L-shape having one end fixed to the plurality of linear bearing bodies and the other end located above the measuring table and at the center between the linear bearing bodies in the direction in which the rail is laid. a measuring arm 32, and a moving mechanism 43, 44, 45 that moves the measuring arm connected to each of the rails via each of the linear bearing bodies in the measuring direction of the object to be measured placed on the measuring stand. , 46, and a distance measuring sensor 36 attached to the other end of the measuring arm to non-contactly measure changes in the distance to the object to be measured while the measuring arm is moving. Flatness measuring device.