JP2000299370A - Sample-holding device and aligner with the sample- holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase acceleration during scanning drive of a sample by holding the sample in a simple way at low cost, without enlarging a contact area between the flat sample and a sample stage. SOLUTION: In a sample-holding device, a reticle 1 as a flat sample is held on a moving stage 2 as a sample stage which is movable horizontally. In this case, the reticle 1 is directly vacuum chucked in a vacuum state on the moving stage 2. A plurality of independent holding members H1, separated physically from the recticle 1 and the moving stage 2, are provided at positions and the reticle 1 is held at a prescribed position of the moving stage 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holding device for mounting a flat sample on a sample stage movable in a direction parallel to the plate surface of the sample and a sample holding device for holding the sample. The present invention relates to an exposure apparatus used. Such a sample holding apparatus is particularly suitable for a holding apparatus for holding a reticle (including a mask) on a moving table, a scanning exposure apparatus using the apparatus, and the like.

[0002]

2. Description of the Related Art Conventionally, a projection system for transferring a part of a pattern formed on a flat sample such as a reticle (including a mask) onto a substrate to be exposed such as a wafer, and a projection system for transferring a pattern on the reticle. An illumination system having a light source for partially irradiating a rectangular or arcuate slit light beam, and a scan mechanism for scanning a reticle and a substrate to be exposed at a constant speed ratio with respect to the slit light beam and the projection system. 2. Description of the Related Art A scanning exposure apparatus which has a reticle and exposes and transfers a pattern on a reticle onto a wafer is known.

FIG. 6 is a schematic structural view showing such a scanning type exposure apparatus. This exposure apparatus includes an irradiation system 26 for converting exposure light from a light source such as a mercury lamp or a laser light source into a slit light beam, and a pattern on a reticle 1 as a flat sample illuminated with the slit light beam by a substrate to be exposed. A projection system 27 for reducing projection onto a certain wafer 28. The reticle 1 is mounted on a reticle holding device installed on a reticle stage 29 as a sample stage that can be moved in the horizontal direction, and is vacuum-adsorbed. A reflecting mirror 31 is mounted on the reticle stage 29, and the position of the reticle stage 29 is measured by the reticle position measuring laser interferometer 30 via the reflecting mirror 31.

On the other hand, the wafer 28 is
Is vacuum-sucked on the wafer chuck 32 mounted on the wafer. A bar mirror 34 is provided on the wafer stage 33, and the wafer stage 3
The position 3 is measured by the wafer position measuring laser interferometer 35.

[0005] An alignment detection system 36 for detecting the relative position between the reticle 1 and the wafer 28 is disposed above the reticle 1, and the exposure apparatus detects the relative position by using the reticle position measurement laser. Interferometer 3
The scanning exposure is performed by synchronizing the position between the reticle 1 and the wafer 28 with the wafer interferometer 35 and the wafer position measurement laser interferometer 35.

The entire apparatus is supported by a main frame 38 mounted on a vibration isolation table 39, and a reticle stage 29 is mounted on a structure 3 disposed on the main frame 38.
7 move on. Then, as shown in FIG. 7, the conventional reticle holding device uses a vacuum pad provided on the reticle holding device for a limited portion of the lower surface of the reticle 1 where there is no pattern (a portion hatched in FIG. 7). 22 was merely vacuum-adsorbed.

[0007]

In the above-mentioned conventional holding device, only a limited portion of the lower surface of the reticle 1 having no pattern is vacuum-sucked on the vacuum pad 22, so that when the suction area is small, In order to improve the productivity by increasing the acceleration during the scanning drive of the reticle stage 29, the reticle holding force (frictional force) between the reticle 1 and the reticle stage 29 generated by vacuum suction is reduced by the inertial force of the reticle 1. There is a possibility that slippage may occur between the reticle 1 and the reticle holding device 29. If the position of the reticle 1 shifts due to such slippage, there is a serious problem that the alignment accuracy is reduced, and in the worst case, the alignment becomes impossible. For this reason, a limit is imposed on the scanning drive acceleration of the reticle stage 29, which hinders improvement in device productivity. In order to increase the reticle holding force, the reticle 1 may be pressed against the reticle stage 29 by an electric or mechanical force. However, when the pressing mechanism is installed on the reticle stage 29, when the reticle 1 is mounted on the reticle stage 29, it is necessary to add a function of retracting the pressing mechanism to the reticle 1 descending from above.
The mechanism becomes complicated. In addition, suction devices that use electrostatic force do not dramatically increase the suction force compared to vacuum suction, and also require expensive electrical components such as high-voltage power supplies, resulting in higher costs for the reticle holding device. Had become.

The present invention has been made in view of the above-described problems, and is simple and inexpensive without increasing the contact area between a flat sample such as a reticle and a sample stage such as a reticle stage. Provided is a sample holding device that firmly holds a sample on a sample stage, increases acceleration during scanning driving of the sample, and can achieve both improvement in productivity and high accuracy, and an exposure apparatus using the holding device. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and achieve the object, the present invention provides a method for mounting a flat sample on a sample stage movable in a direction parallel to the plate surface of the sample. In the sample holding device for holding the sample, the sample and the sample stage are physically separated from each other, and the sample is held on the sample stage by an independent holding tool. In the present invention, the sample is directly vacuum-adsorbed onto the sample table, and the sample and the sample table are physically separated from each other with an independent holding tool, and the sample is held on the sample table. Alternatively, the independent holding tool may hold the sample on the sample table by a vacuum suction force, and the independent holding tool sucks the sample onto the sample table by the vacuum suction force and simultaneously holds the sample on the sample table. The independent holding tool may be pressed against the sample table while being attracted to the sample table by magnetic attraction.

Further, the present invention has a vacuum supply control means for controlling a vacuum suction force, a transfer means for transferring the independent holding tool onto the sample table, and an exposure means. It can also be applied to an exposure apparatus that transfers a pattern onto a substrate to be exposed, and includes magnetic control means for controlling magnetic attraction, transport means for transporting the independent holding tool onto the sample table, and exposure means. The present invention can also be applied to an exposure apparatus that transfers a pattern on the sample onto a substrate to be exposed.

[0011]

According to the present invention, the flat sample is a reticle,
When the reticle is applied to a scanning type exposure apparatus that holds the reticle against a reticle stage as a sample stage, a portion having no pattern on the reticle lower surface is sucked to the reticle stage by a conventional suction means, and the exposed portion on the reticle upper surface is An appropriate part on the reticle stage is physically separated from the reticle and the reticle stage, and the reticle can be firmly held on the reticle stage by independent independent holding tools.

By mounting such a reticle holding device on a reticle stage of a scanning type exposure apparatus, the reticle can be held in a stable state on the reticle stage, and the position of the reticle can be prevented from shifting during exposure. it can. As a result, the transfer accuracy of the scanning type exposure apparatus can be improved, and it can greatly contribute to an improvement in productivity due to a higher speed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking as an example a case where a flat sample is a reticle and applied to a scanning exposure apparatus. (Embodiment 1) FIG. 1 is a plan view showing a reticle stage portion of a scanning type exposure apparatus equipped with a reticle holding device according to a first embodiment of the present invention, and FIG. 2 is a cross sectional view of FIG. . In FIG. 1, a reticle 1 is held on a moving table 2 as a sample table having a reticle holding device. The moving table 2 is disposed above a base 3 fixed to a fixed portion, and is mounted on both sides of a reticle 1 along two straight and continuous stators 4 and 4 of linear motors as drive actuators provided on both sides. 1 can be moved in a direction parallel to the surface (up and down in FIG. 1). On both sides of the movable base 2, movers 5 corresponding to the respective stators 4 of the linear motor are arranged.

The reticle holding apparatus has four independent holding tools H1 which are physically separated from the reticle 1 and the moving table 2 and are independent of each other. The independent holding tool H1 includes the independent members 6 and 7, And a leaf spring 8 for connecting the independent members 6 and 7 to each other. As shown in FIG. 2, the independent member 6 is provided with a vacuum groove 6a on a surface in contact with the moving table 2, and the independent member 7 is provided with a vacuum groove 7 on a surface in contact with the reticle 1.
a is provided, and the vacuum grooves 6 of the independent members 6 and 7 are provided.
The vacuum spaces in the vacuum chambers a and 7a are communicated with each other by a vacuum tube 9 passing directly above the vacuum space, and the vacuum space in the vacuum grooves 6a and 7a is communicated with the vacuum supply path 19a provided in the movable base 2 and the vacuum supply path 19a. It can communicate with a vacuum source 21 via a connected pipe 19 and a vacuum valve control device 20.

The independent members 6 and 7 are desirably made of a metal, ceramic or the like having a low specific gravity, and relatively inexpensive aluminum can be used. Is set to be larger than the contact area where the independent member 7 contacts the reticle 1.

The leaf spring 8 functions as a rigid body in the direction in which the movable table 2 moves, and the independent member 6 and the independent member 7 do not relatively displace and the direction perpendicular to the direction in which the movable table 2 moves ( In the direction perpendicular to the paper surface in FIG. 1), the two independent members 6 and 7 are connected so that the independent members 6 and 7 can be relatively elastically displaced. .

The reticle holding device according to this embodiment comprises a separate holding member H1 having independent members 6 and 7, a leaf spring 8 and a vacuum tube 9, and a vacuum pad 22 similar to the conventional one. Adsorption is also used. The vacuum pad 22 is connected to a vacuum supply path 18a provided in the moving table 2 and a pipe 18 connected to the vacuum supply path 18a.
0 can communicate with the vacuum source 21.

The scanning type exposure apparatus provided with the reticle holding device according to the above embodiment of the present invention is fixed on the reflecting mirror 10 on the moving table 2 and on the optical axis of the laser beam toward the moving table 2. Interferometer 11, detector 1 arranged on interferometer 11
2. It has a light splitter 13 for splitting the optical axis of the exposure laser light into straight light and reflected light, a bending mirror 14, and the like. Then, in order to measure the position of the moving table 2, the laser beam emitted from the laser head 15 is a light that travels straight along the optical axis for measuring the position of the moving table 2 on the central axis of the reticle 1 by the light splitter 13. The optical axis that travels straight is bent in the direction of the moving table 2 by a bending mirror 14 placed on the optical axis at a position away from the central axis. An interferometer 11 is fixed on the optical axis of each of these laser beams directed toward the moving table 2, and a reflecting mirror 10 is mounted on the moving table 2. A detector 12 is arranged in each interferometer 11 so that the position of the movable base 2 and the rotation in the horizontal direction can be measured.

Next, the operation of the scanning type exposure apparatus having the reticle holding device will be described with reference to FIG. The movable table 2 is guided vertically and horizontally in a non-contact manner by the base 3 via the horizontal support static pressure pad 16 and the vertical support static pressure pad 17, and moves in the vertical direction with respect to the plane of FIG. It is possible.

Now, the reticle 1 is positioned on the vacuum pad 22 by an alignment detection and reticle driving system (not shown) with respect to a reticle reference mark (not shown) placed on the reference portion of the exposure apparatus. Device 20
From the vacuum source 21 by the vacuum controller including
The vacuum pad 22 is evacuated through the vacuum pad 8 and the vacuum supply path 18a, and the reticle 1 is vacuum-adsorbed to the vacuum pad 22.
Next, the independent holding tools H1 including the independent members 6 and 7, the plate spring 8, and the vacuum tube 9 are set over the moving table 2 and the reticle 1 by a transport system (not shown). The transport system of the independent holding tool H1 can also be used as a reticle transport system.

Here, the vacuum source 2 is controlled by the vacuum controller.
1 through a vacuum pipe 19 and a vacuum supply path 19a,
The space where the independent member 6 and the moving table 2 come into contact with each other is evacuated, and the independent member 6 is vacuum-sucked to the moving table 2. Then, the space where the independent member 7 contacts the reticle 1 is also evacuated by the vacuum tube 9, and as a result, the reticle 1 is vacuum-adsorbed by the independent member 7 together with the vacuum pad 22. At this time, the contact area between the independent member 6 and the moving table 2 is large, and therefore the suction force can be set large. Therefore, if the slip here is ignored, the reticle 1 is moved to the moving table 2.
The reticle holding force Fh for holding the reticle in the moving direction is f1 for the reticle suction force of the vacuum pad 22, f2 for the reticle suction force of the independent member 7, and the lower surface of the reticle 1 and the vacuum pad 22.
, The friction coefficient between the upper surface of the reticle 1 and the independent member 7 is μ2, and the weight of the reticle 1 is W,
If the weight of the independent member 7 is ignored, it is expressed by the following equation (1).

[0022]

(Equation 1) Here, the suction area of the upper surface of the reticle 1 is less restricted than the suction area of the lower surface of the reticle, and the friction coefficient μ2
Can also be increased by surface processing or the like, so that f1 and f1
2. The magnitude relationship between μ1 and μ2 is expressed by the following equation (2).

[0023]

(Equation 2) Therefore, Equation 1 is represented by Equation 3 below.

[0024]

(Equation 3) From equation (3), the reticle holding force Fh according to this embodiment is obtained.
Can be set to be twice or more the size of the conventional holding device excluding the reticle weight.

When the movable table 2 is driven in synchronization with the wafer stage to perform exposure, the force Fr acting on the reticle 1 when the movable table 2 is accelerated or decelerated is represented by α, where the acceleration / deceleration of the movable table 2 is α. It is expressed by the following equation (4).

[0026]

(Equation 4) At this time, in order to hold the reticle 1 so as not to be displaced, the area where the independent member 7 contacts the upper surface of the reticle 1 and the degree of vacuum are set so that Fh> Fr.

Next, when exposing is completed and the reticle 1 is replaced, the vacuum supply to the vacuum pad 22 and the independent member 6 is cut off by the vacuum control device including the vacuum valve control device 20, and the reticle 1 is released to the atmosphere. After that, the independent holding tool H1 and the reticle 1 are carried out by a reticle transport system (not shown), and only the reticle 1 is replaced.

According to this embodiment, the independent members 6 and 7 can be made of an inexpensive material.
The design is easy and simple because it is only required to be rigid in the direction in which the moving table 2 moves. Further, the independent members 6 and 7, the leaf spring 8 and the vacuum tube 9 constituting the independent holding tool H1 of the reticle holding device can be made of a small number of parts and light materials, and use a conventional reticle transport system. Is possible. Further, there is an advantage that a conventional vacuum source can be used.

(Embodiment 2) FIG. 3 is a cross-sectional view showing a reticle stage portion of a sample holding device according to a second embodiment of the present invention. In this embodiment, the independent holding tool H2 includes a steel ball 25 for pressing the reticle 1 against the vacuum pad 22 by point contact, an independent member 23 having a vacuum groove 23a for vacuum suction to the moving table 2, and a steel ball. And a leaf spring 24 for connecting the independent member 23 to the independent member 23. The vacuum space in the vacuum groove 23a is
Can be connected to a vacuum source 21 via a vacuum supply path 19a provided in the apparatus, a pipe 19 connected to the vacuum supply path 19a, and a vacuum valve control device 20. 3, the same parts as those in FIG. 2 are denoted by the same reference numerals, and redundant description of those parts will be omitted.

In this reticle holding device, when the independent member 23 is vacuum-sucked to the moving table 2, the leaf spring is deformed,
Steel ball 25 presses reticle 1 against vacuum pad 22.
Therefore, the vacuum pad 22 may suck the reticle 1 by vacuum, or may simply support the lower surface of the reticle 1 without sucking the reticle. The leaf spring 24 efficiently converts the attraction force generated between the independent member 23 and the moving table 2 into a force for pressing the reticle 1 against the vacuum pad 22, and the maximum attraction force is 1.
The reticle 1 can be pressed against the vacuum pad 22 with a force of / 2.

According to the second embodiment, as compared with the method of vacuum-sucking a limited portion of the reticle 1 having no pattern, the plane on the movable base 2 and the independent member
Reticle 1 using vacuum pad 2
2, the reticle 1 can be held more firmly.

(Embodiment of Device Manufacturing Method) Next, an example of a method of manufacturing a device using a scanning type exposure apparatus having a reticle stage having the above reticle holding device will be described. FIG. 4 is a diagram showing a manufacturing flow of a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD). Step 1
In (Circuit Design), we design circuits for semiconductor devices,
Step 2 (mask fabrication) forms a mask on which the designed circuit pattern is formed. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon.

Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the mask and wafer prepared in the above steps. The next step 5 (assembly) is called a post-process, and is a process of producing semiconductor chips using the wafer manufactured in step 4, and includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. Process. In step 6 (inspection), inspections such as an operation check test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 5 shows the wafer process (step 4).
It is a figure which shows the detailed flow of. Step 11 (oxidation step) oxidizes the wafer's surface. Step 12 (C
In the VD process), an insulating film is formed on the surface of the wafer. In step 13 (electrode forming step), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation step), ions are implanted into the wafer. In step 15 (resist processing step), a photosensitive agent is applied to the wafer.

In the step 16 (exposure step) after the above-described wafer surface treatment step, the circuit pattern of the mask is printed on the wafer by exposure using the scanning exposure apparatus according to the present invention. Next, in step 17 (development step), the exposed wafer is developed, and in step 18 (etching step), portions other than the resist image developed in step 17 are scraped off. In the final step 19 (resist stripping step), unnecessary resist after etching is removed.

Further, by repeating steps 11 to 19, multiple circuit patterns are formed on the wafer.

By employing the device manufacturing method according to the above embodiment of the present invention, it is possible to manufacture a highly integrated semiconductor device, which has been conventionally difficult to manufacture, with high productivity.

The present invention is not limited by the above embodiment, and various modifications and changes can be made. For example, in the second embodiment, the independent member 23 is vacuum-sucked to the moving table 2, but a magnet is embedded in the independent member 23, and the opposite surface of the moving table 2 is made of a magnetic material such as iron or a magnet. Alternatively, a magnetic attraction method may be used. In this case, if a rare earth magnet is used, it is possible to obtain an attraction force of about 5.5 atm on the adsorption surface at the maximum. Further, it can be used in a vacuum and can be applied to a reduced X-ray exposure apparatus and the like. The number of independent holding tools H1 and H2 used is not limited to four, but may be two or three, or may be five or more.

[0039]

The present invention has the following effects. Along with the conventional method of vacuum-sucking a flat sample onto a sample stage, the vacuum-suction source or magnet is used as an adsorption source, and the sample and sample stage are physically separated from the sample and sample stage with independent holding tools. Can be firmly and stably maintained. Further, since the independent holding tool can be adsorbed on the sample table after being mounted on the sample and the sample table, there is no need for a complicated mechanism such as retreating to the sample when mounting the sample. In a scanning type exposure apparatus using such a sample holding device, it is possible to prevent the sample from being displaced during exposure, so that it is possible to improve the transfer accuracy of the scanning type exposure apparatus, and furthermore, when driving the sample stage. The acceleration can be set to be large, and the productivity of the device due to the high speed can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a reticle stage on which a reticle holding device according to a first embodiment of the present invention is mounted.

FIG. 2 is a cross-sectional view of a reticle stage portion of FIG.

FIG. 3 is a cross-sectional view of a reticle stage on which a reticle holding device according to a second embodiment of the present invention is mounted.

FIG. 4 is a flowchart of a method for manufacturing a semiconductor device using an exposure apparatus equipped with a reticle holding device according to an embodiment of the present invention.

FIG. 5 is a diagram showing a detailed flow of the wafer process of FIG. 4;

FIG. 6 is an elevational view showing a scanning exposure apparatus using a conventional reticle holding device.

FIG. 7 is a perspective view showing a schematic configuration of a conventional reticle holding device.

[Explanation of symbols]

H1: independent holding tool, H2: independent holding tool, 1: reticle, 2: moving table, 3: base, 4: linear motor stator, 5: linear motor mover, 6: independent member, 6a:
Vacuum groove, 7: independent member, 7a: vacuum groove, 8: leaf spring,
9: vacuum tube, 10: reflecting mirror, 11: interferometer, 1
2: detector, 13: light splitter, 14: folding mirror, 1
5: laser head, 16: horizontal static pressure pad, 1
7: vertical static pressure pad, 18: pipe, 18a: vacuum supply path, 19: pipe, 19a: vacuum supply path, 20: vacuum valve controller, 21: vacuum source, 22: vacuum pad, 2
3: independent member, 23a: vacuum groove, 24: leaf spring, 25:
Steel ball, 26: illumination system, 27: projection system, 28: wafer, 2
9: reticle stage, 30: reticle position measurement laser interferometer, 31: reflecting mirror, 32: wafer chuck, 3
3: Wafer stage, 34: Bar mirror, 35: Wafer position measurement laser interferometer, 36: Alignment detection system,
37: structure, 38: body, 39: anti-vibration table.

Claims (7)

[Claims] 1. A sample holding apparatus for mounting a sample on a plate and holding the sample on a sample stage movable in a direction parallel to the plate surface of the sample. A sample holding device, wherein the sample is held on the sample stage by a separate and independent holding tool. 2. A sample holding apparatus which mounts a sample on a plate and holds the sample on a sample stage movable in a direction parallel to the plate surface of the sample, wherein the sample is directly placed on the sample stage. A sample holding apparatus, wherein the sample is held on the sample stage by vacuum independent suction and physically separated from the sample and the sample stage by an independent holding tool. 3. The sample holding device according to claim 1, wherein the independent holding tool holds the sample on the sample table by a vacuum suction force. 4. The sample holding device according to claim 1, wherein the independent holding tool is pressed against the sample table while being suctioned to the sample table by a vacuum suction force. 5. The sample holding apparatus according to claim 1, wherein the independent holding tool is attracted to the sample table by magnetic attraction and simultaneously presses the sample against the sample table. 6. A sample table having the sample holding device according to claim 1, a vacuum supply control means for controlling a vacuum suction force, and a device for transferring the independent holding tool onto the sample table. An exposure apparatus, comprising: a transport unit of (1); and an exposure unit, wherein the pattern on the sample is transferred onto a substrate to be exposed. 7. A sample table having the sample holding device according to claim 5, magnetic control means for controlling magnetic attraction, transport means for transporting the independent holding tool onto the sample table, and exposure means. An exposure apparatus, comprising: transferring a pattern on the sample onto a substrate to be exposed.