JPH0473294B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement of a sample holding table device equipped with a θ table for correcting the inclination of a sample.

[Technical background of the invention and its problems]

In IC manufacturing, if a master mask or reticle has a defect such as a pattern breakage, a desired semiconductor element cannot be obtained, resulting in a decrease in yield. For this reason, pattern defect inspection apparatuses have conventionally been used that automatically inspect pattern defects in master masks, reticles, and the like. In this device, a sample such as a master mask or reticle is fixedly held on a table, and this table is moved in the X and Y directions and rotated in the θ direction to correct the position and tilt of the sample relative to reference marks, etc. Afterwards, desired inspections are performed.

1 and 2 schematically show the structure of a sample holding table device used in this type of apparatus. FIG. 1 is a plan view, and FIG.
It is an A sectional view. A θ table 3 on which a sample 2 is fixedly held is placed on the XY table 1 . The θ table 3 is supported on the X-Y table 1 by a preload spring 4 and a presser roller 5, and
It is fixed by sliding friction on the guide surface on the table 1. Further, a driving section consisting of a motor 6 and a micrometer head 9 is provided on the X-Y table 1, and the .theta. table 3 can be rotated by this driving section. And X-Y
The position of the sample 2 is defined by the movement of the table 1, and the tilt of the sample 2 is corrected by the rotation of the θ table 3.

However, such a conventional table device has a problem in that it is not possible to simultaneously obtain high positioning accuracy of the θ table 3 and high stability after positioning. That is, in order to achieve high positioning accuracy of the θ table 3, the coefficient of friction on the guide surface must be extremely small, and on the other hand, in order to obtain high stability after positioning, the coefficient of friction on the guide surface must be large. It is desirable. When the θ table 3 is held by the presser roller 5 described above, the coefficient of friction on the guide surface is constant when it is fixed and when it is rotated. For this reason, the current situation is that either the positioning accuracy of the θ table 3 or the stability after positioning is sacrificed. Therefore, when such a table device is used in a pattern defect inspection device, an error in the tilt of the sample occurs due to positioning errors and slippage of the θ table 3 due to the movement of the X-Y table, which impairs inspection accuracy. This will lead to a decrease in
Note that the above-mentioned problem is not limited to table devices for pattern defect inspection, but also applies to various table devices that require correction of the inclination of a sample.

[Purpose of the invention]

An object of the present invention is to provide a sample holding table device that can obtain high positioning accuracy of a θ table and high stability after positioning, and can contribute to improving the inspection accuracy of a pattern defect inspection device.

[Summary of the invention]

The gist of the present invention is to utilize the floating effect of the table by compressed gas and the vacuum chuck to vary the coefficient of friction on the guide surface of the θ table between when it is fixed and when it is rotated.

That is, the present invention provides a sample holding table device which includes a θ table for fixedly holding a sample placed on a base, and has a function of fixing the θ table on the base and a function of rotating the θ table. The base is provided with a supply and exhaust hole that penetrates through the base and opens at the contact part of the base with the θ table, and when the θ table is fixed, the supply and exhaust hole is evacuated to place the θ table on the base. When the .theta. table is rotated, compressed gas is introduced into the air supply/exhaust hole to float the .theta. table.

〔Effect of the invention〕

According to the present invention, when the θ table is rotated, the θ table can be held on the base with extremely small frictional force by floating the table.
θ with smooth movement without stick slip etc.
The table can be rotated. For this reason, θ
The positioning accuracy of the table can be improved, and the tilt of the sample can be corrected with high precision. Also,
When fixing the θ table, the vacuum force of the vacuum chuck allows the θ table to be fixed and held on the base with an extremely large frictional force, which reliably prevents the θ table from moving due to the inertial force caused by the acceleration/deceleration that occurs when the base stops moving. can do. In other words, it is possible to improve the stability after alignment of the θ table. In addition, pattern defect inspection equipment uses an air line for autofocus and a vacuum line for a vacuum chuck, and if the present invention is applied to this type of equipment, air to the air supply/exhaust hole in the base is used. This has the advantage that each of the above lines can be used in common for introduction or vacuuming.

[Embodiments of the invention]

3 and 4 each show a schematic configuration of an embodiment of the present invention, with FIG. 3 being a plan view and FIG.
The figure is a sectional view taken along the line BB in FIG. 3. 11 in the diagram
is a base with a notch in the center, and a θ table 12 is placed on this base 11. Inside the base 11 is a through hole for air supply and exhaust (air supply and exhaust hole).
13 is provided, and this air supply/exhaust hole 13 is connected to the θ table 12 on the upper surface of the base 11.
There are openings at several locations, and further openings at the side surfaces of the base 11. A recessed portion 14 including the opening 13 is formed in the upper surface of the base 11 at a contact portion with the θ table 12 . Compressed air is introduced into the air supply/exhaust port 13 from a side opening of the base 11, or the air is evacuated. The θ table 12 is formed by cutting out a rectangular central portion of a disc body, and the θ table 12 is provided with exhaust holes 15 that open at the top and side surfaces thereof. Then, the exhaust hole 15 is set to θ
By drawing a vacuum through the side opening of the table 12, the sample 16 is vacuum chucked onto the θ table 12.

On the other hand, on the upper surface of the base 11, four guide sections 17 for guiding and holding the .theta. table 12 and a drive section 18 for rotating the .theta. table 12 are provided, respectively. The guide portion 17 is shown in FIG. 5 in the direction of arrow C in FIG.
As shown in the -C cross section, it consists of a fixed shaft 19, a press roller 20 made of stainless steel, a preload spring 21, a nut 22, etc., and the press roller 20 is in contact with the side surface of the θ table 12, and the θ table 12 is attached to the base 11. held on top. The drive unit 18 consists of a pulse motor 23 and a micrometer head 24 that converts the rotation of this motor 23 into linear motion. has been done. And this micrometer head 2
4, the θ table 12 rotates. In the figure, reference numeral 26 indicates a coupling for connecting the motor 23 and the micrometer head 24, and reference numeral 27 indicates a spring that holds the micrometer head 24 and the arm 25 in contact with each other.

With such a configuration, by introducing compressed air into the supply/exhaust hole 13 when aligning the θ table 12, an air film is formed between the θ table 12 and the base 11, and the θ table 12 is slightly It will surface. Therefore, the friction between the θ table 12 and the base 11 becomes extremely small.
The θ table 12 can be smoothly rotated by the drive unit 18. Therefore, θ table 1
2 can be positioned with high precision, and sample 1 can be positioned with high precision.
6 can be reliably corrected. Also,
After the positioning of the .theta. table 12 is completed, the .theta. table 12 is vacuum-chucked onto the base 11 by evacuating the air supply/exhaust hole 13. Therefore, the θ table 12 and the base 11
The friction between the θ table 12 and the θ table 12 can be made extremely large, and problems such as movement of the θ table 12 will not occur even with the inertial force caused by the acceleration/deceleration caused by the stoppage of the movement of the base 11. Therefore, the stability of the θ table 12 after alignment can be improved. Further, compared to conventional devices, there is an advantage that it can be realized with a simple structure that only requires adding the supply/exhaust hole 13.

FIG. 6 is a schematic configuration diagram showing another embodiment in which the present invention is applied to a pattern defect inspection apparatus. In addition,
The same parts as in FIGS. 3 and 4 are given the same reference numerals, and detailed explanation thereof will be omitted. In this embodiment, the air supply/exhaust hole 13 provided in the base 11 and θ
Each of the exhaust holes 15 provided in the table 12 had one side opening. Further, as the sample 16, a reticle was used. Furthermore, although the base 11 is shown simply in the figure, it is placed on an X table that is movable in the X direction (horizontal direction in the paper) in the Y direction (horizontal direction in the paper).
The so-called X-Y
It is assumed that it consists of a table.

An optical lens barrel 33 equipped with an objective lens 31, a photodetector element 32, etc. is arranged above the reticle 16, and this optical lens barrel 33 is fixed to a fixed end via an elastic member 34. Furthermore, the optical lens barrel 33 includes a motor 35, a worm 36, and a worm wheel 3.
7 and a screw 38, etc., to move it up and down. An air introduction hole 39 and an air outlet hole 40 are provided at the bottom of the optical barrel 33,
The introduction hole 39 has an air chamber 4 equipped with a pressure sensor 41.
Compressed air is introduced from a compressed air cylinder 43 via 2. A throttle 50 is provided at the entrance of the air chamber 42. Then, the reticle 16 is measured by a so-called air micrometer consisting of the introduction hole 39, the outlet hole 40, the air chamber 41, the pressure sensor 42, etc.
The distance between the optical lens barrel 33 and the lower surface of the optical lens barrel 33 is detected.

On the other hand, the supply/exhaust hole 13 of the X-Y table 11
The compressed air cylinder 43 is connected via an electromagnetic valve 44, and the vacuum pump 46 is connected via an electromagnetic valve 45. Also, the above θ
The vacuum pump 46 is connected to the exhaust hole 15 of the table 12 via an electromagnetic valve 47. In addition, in the figure, 48 indicates a light source, and 49 indicates a condensing lens.

In the pattern defect inspection apparatus configured in this way, first, the X-Y table 11 and the θ table 12 are
The position and inclination of the reticle 16 are corrected by the movement of the reticle 16 . That is, after moving the X-Y table 11 in the X direction and the Y direction, the electromagnetic valves 44 and 47
is opened and the reticle 16 is fixedly held on the θ table 12 with the electromagnetic valve 45 closed.
The θ table 12 is floated. Then, as in the previous embodiment, the θ table 12 is rotated to correct the inclination of the reticle 12. After the inclination of the reticle 16 is corrected, close the electromagnetic valve 44,
Open the electromagnetic valve 45. As a result, θ table 1
2 will be vacuum chucked onto the X-Y table 11. After this, pattern defect inspection is performed through normal operations. That is, the reticle 16
The pattern on the reticle 16 is inspected by spot-irradiating light from a light source 48 onto the reticle 16 and focusing the transmitted light on the light receiving surface of the photodetecting element 32 using the objective lens 31. If the reticle 16 has vertical movement such as warpage, this displacement is detected by the air micrometer, and the optical lens barrel 33 is moved up and down by the drive mechanism to follow the warp or the like of the reticle 16. automatic focusing is performed.

Therefore, even if the reticle 16 undergoes vertical movement such as warping, pattern inspection can be performed with high accuracy. In addition, when correcting the inclination of the reticle 16, θ
By levitating the table 12, further
- When moving Y table 11, this table 1
By vacuum chucking the θ table 12 on the θ table 1, it is possible to improve both the positioning accuracy of the θ table 12 and the stability after positioning, as in the previous embodiment. Further, in this embodiment, there is no need to provide a special air line or the like to insert air into the air supply/exhaust hole 13 when the θ table 12 rotates, and an air micrometer normally used in pattern defect inspection equipment can be used. A compressed air cylinder 43 for introducing air can be shared. Similarly, the vacuum pump 46 for the vacuum chuck of the reticle 16 can be shared, without the need to provide a special vacuum line or the like to evacuate the supply/exhaust hole 13 when the θ table 12 is fixed.

Note that the present invention is not limited to the embodiments described above. For example, the guide portion may be of any type as long as it can come into contact with the side surface of the θ table and guide and hold the table on the base, and may have a configuration as shown in FIG. 7. Alternatively, it may be a mechanism that rotates the table around an axis. Furthermore, the number of supply and exhaust holes provided in the base, the number of openings on the top surface of the base, etc. may be determined as appropriate according to specifications. Further, the fixing and holding of the sample by the θ table is not limited to a vacuum chuck, and a fixing member or an electrostatic chuck may also be used. Further, the shape, size, etc. of the θ table can be changed as appropriate according to specifications. Furthermore, in the embodiment shown in FIG.
9 may be placed above the table 12 and upside down. The present invention is not limited to pattern defect inspection, but can be applied to various table devices that require correction of sample inclination. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a schematic configuration of a conventional sample holding table device, and Fig. 2 is a view taken along arrow A-A in Fig. 1.
3 is a plan view showing a schematic configuration of an embodiment of the present invention, and FIG. 4 is a view taken along arrow B-B in FIG. 3.
5 is a cross-sectional view taken along the line CC in FIG. 3, FIG. 6 is a schematic configuration diagram showing another embodiment in which the present invention is applied to a pattern transfer device, and FIG. It is a sectional view for explaining a modification. 11...base (X-Y stage), 12...θ table, 13...supply/exhaust hole, 14...recess, 15...exhaust hole, 16...sample (reticle), 17...guide section,
18... Drive unit, 43... Compressed air cylinder, 44, 4
5, 47... Solenoid valve, 46... Vacuum pump.

Claims (1)

[Scope of Claims] 1. A table placed on a base to fixedly hold a sample; and a guide provided on the base to guide and hold the table in a rotational direction by pressing at least one point on the periphery of the table. a rotation drive unit provided on the base to rotate the table; and an intake/exhaust hole provided through the base and opened at a contact portion of the base with the table; A sample holding table characterized in that when the table is fixed, the table is vacuum-chucked by evacuating the suction and exhaust holes, and when the table is rotated, compressed gas is introduced into the suction and exhaust holes to levitate the table. Device. 2. The base according to claim 1, wherein the base includes an X table movable in the X direction and a Y table placed on the X table and movable in the Y direction. Table device for holding samples. 3. The table is equipped with an exhaust hole for fixing and holding the sample, and the exhaust hole is connected to the same vacuum pump as the intake and exhaust holes provided in the base. A sample holding table device according to claim 1. 4. A disc-shaped table placed on a base to fixedly hold the sample, and a guide provided on the base to guide and hold the table in the rotating direction by pressing the peripheral part of the table toward the center and toward the base. Department and
a rotation drive unit provided on the base to rotate the table; and an intake/exhaust hole provided through the base and opened at a contact portion of the base with the table and near the periphery of the table. characterized in that when the table is fixed, the table is vacuum-chucked by evacuating the suction and exhaust holes, and when the table is rotated, compressed gas is introduced into the suction and exhaust holes to levitate the table. A table device for holding samples. 5. The base according to claim 3, wherein the base comprises an X table movable in the X direction and a Y table placed on the X table and movable in the Y direction. Table device for holding samples. 6. The table is equipped with an exhaust hole for fixing and holding the sample, and the exhaust hole is connected to the same vacuum pump as the intake and exhaust holes provided in the base. A sample holding table device according to claim 3.