JPH1092736A - Proximity aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the interference between a substrate and an original plate such as a mask in step-moving the substrate by making a holding surface for sucking the substrate of substrate holding means to have a convex shape. SOLUTION: A proximity aligner has a wafer stage 1 which is a substrate holding means and a mask stage 2 which is original board holding means, for holding a wafer W1 as a substrate and a mask M1 as an original plate closely to each other, respectively. The wafer stage 1 has a wafer chuck 10, having a suction surface 10a as a holding surface for sucking the wafer W1 , and an XY stage 30 for supporting the wafer chuck 10 via a tilt stage 20. The suction surface 10a of the wafer chuck 10 is a spherical surface finished with high precision, and has a plurality of concentrically arranged suction grooves as a suction means. These suction grooves are vacuum-sucked by a vacuum pump connected with an internal pipe arrangement, thus generating a vacuum suction force for sucking the wafer W1 to the suction surface 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called proximity exposure apparatus which performs exposure in a state where a mask and a wafer are brought close to a minute space.

[0002]

2. Description of the Related Art In exposure apparatuses for manufacturing semiconductor devices, in recent years, exposure apparatuses using short-wavelength exposure light such as X-rays have been developed in order to cope with further miniaturization. In an exposure apparatus using X-rays as exposure light, a so-called proximity exposure method in which exposure is performed in a state in which a mask and a wafer are brought close to a minute interval of, for example, several tens of μm is generally used. Also, the smaller the distance between the wafer and the mask, ie, the smaller the exposure gap, the higher the resolution tends to be. For example, if the line width of the transfer pattern is 0.1 μm or less, a sufficient resolution cannot be obtained unless the exposure gap is 10 μm or less.

FIG. 6 shows an X-ray proximity exposure apparatus that uses X-rays such as synchrotron radiation (charged particle storage ring radiation), which places a wafer W ₀ and a mask M ₀ close to each other. Wafer stage 1 to hold each
01 and the mask stage 102 has a wafer W ₀ and the alignment optical system 103 for measuring the displacement of the distance and both of the mask M _0, they are supported through an anti-vibration device 104a in the exposure chamber 104 It is supported by the support 105.

[0004] X-rays L ₀ as charged particle storage ring radiation emitted from a light source (not shown) are introduced into an exposure chamber 104 through a beam duct 106 controlled to a high vacuum.
Exposing the wafer W ₀ through the mask M _0. Exposure room 104
Is controlled to a reduced pressure atmosphere of helium gas, and a beryllium window 107 is provided between the high-vacuum beam duct 106 to shut off both atmospheres.

The beryllium window 10 extends from the beam duct 106.
The X-ray L ₀ introduced into the exposure chamber 104 through 7 is magnified by a magnifying mirror (not shown), and has an intensity distribution in the vertical direction (Y-axis direction) in the figure, so that the exposure unevenness on the wafer W ₀ Occurs. Therefore, the shutter 108 is disposed on the upstream side of the mask M _0, to adjust the exposure time by controlling the moving speed of the shutter 108 by the driving section 108a, and is configured to eliminate the exposure unevenness.

[0006] The wafer stage 101, wafer chuck 110 having a suction surface 110a for adsorbing the wafer W ₀
And the wafer chuck 11 via the tilt stage 120
It has an XY stage 130 supporting 0. Tilt stage 120, the rear surface of the wafer chuck 110 has three Z drive portion 120a of each reciprocating movement of the X-ray L ₀ in the optical axis direction (Z axis direction) in the three points on the concentric circles, these driving amount If the distances are the same, the distance between the wafer W ₀ and the mask M ₀ changes, and the tilt angle of the wafer W ₀ and its direction can be adjusted by individually controlling the driving amount of each Z drive unit 120a. It is free.

The XY stage 130 has a Y stage that can reciprocate in the Y-axis direction along a guide 130a, and an X stage that can reciprocate in the X-axis direction on the Y stage. Performs a step movement for sequentially moving each exposure angle of view of the wafer W _{0 to} the exposure position, and serves to correct a positional deviation between the wafer W ₀ and the mask M ₀ based on an output of the alignment optical system 103. .

The suction surface 110a of the wafer chuck 110
Is a flat surface that is finished to a high surface accuracy, this by adsorbing the wafer W _0, to correct the flatness of the wafer W _0. Since the suction surface 110a of the wafer chuck 110 suctions the back surface of the wafer W ₀ , even if the suction surface 110a of the wafer chuck 110 is, for example, a flat surface perpendicular to the X-ray L ₀ that is the exposure light, If the thickness of the wafer W ₀ is not uniform, the surface of the wafer W ₀ , that is, the exposure surface cannot be made perpendicular to the exposure light. Therefore, the inclination of the exposure surface of the wafer W ₀ is measured by the alignment optical system 103, and the tilt stage 120 is driven to correct the inclination of the exposure surface of the wafer W ₀ as described above.

In the proximity exposure method, as described above, the plurality of exposure angles of view of the wafer W ₀ are sequentially changed to the X-rays L _0.
So-called step-and-repeat of the irradiation area that is moved stepwise to an exposure position opposed to the mask M ₀ exposure is common. Exposure mask M ₀ and wafer W ₀
Is set to, for example, about 10 μm, the above-described step movement is performed as follows.

With the wafer W ₀ and the mask M ₀ set to an exposure gap of about 10 μm, as shown in FIG.
During the step movement of the wafer W ₀ , the thick part may interfere with the mask M ₀ . Therefore, as shown in FIG. 7B, the wafer W ₀ is moved from the exposure position shown in FIG. 7A to a predetermined retracted position (for example, the gap with the mask M ₀ is 100 μm).
), The XY stage 130 is driven, and the wafer W ₀ is step-moved as shown in (c) to move the next exposure angle of view to the exposure position facing the mask M ₀ . Move. Then, as shown in FIG. 7 (d), to correct the inclination of the exposure surface of the wafer W ₀ by driving the tilt stage 120, to approximate way, the wafer W ₀ and the mask M ₀ shown in (e) Then, the exposure gap is set as described above, and the exposure cycle is repeated.

[0011]

However, according to the above-mentioned prior art, a step of setting an exposure gap every time the wafer is moved stepwise is required, which increases the exposure cycle time and improves the throughput. It is a major obstacle to the above. In addition, when the thickness unevenness of the wafer is large, there is a possibility that a frame or the like on the outer peripheral portion of the mask may come into contact with the wafer when the wafer is stepped away from the mask. If the retreat position of the wafer is set far away from the mask in order to avoid this, the time required for the step of setting the exposure gap is further increased, and the throughput is further reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and avoids troubles such as interference between a substrate and an original such as a mask when stepping a substrate such as a wafer. It is another object of the present invention to provide a proximity exposure apparatus capable of greatly improving the throughput.

[0013]

In order to achieve the above object, a proximity exposure apparatus according to the present invention comprises: an original holding means for holding an original; a substrate holding means having a holding surface for sucking a substrate; Driving means for moving the substrate holding means to position the substrate with respect to the original plate,
The holding surface of the substrate holding means has a convex shape protruding toward the original.

The difference between the height of the center and the height of the outer peripheral portion of the holding surface is preferably equal to or more than the allowable value of uneven thickness of the substrate.

Further, it is preferable that the holding surface has concentric suction means for sucking the substrate.

[0016]

If the holding surface of the substrate holding means has a convex shape such as a spherical surface, the interval between the most protruding portion of the holding surface, for example, the exposure angle of view located at the center and the original is set as the exposure gap.

When the substrate is step-moved to expose the next exposure angle of view, there is no danger of interference with the original even if the substrate is step-moved with the exposure gap kept away from the original.

That is, the next exposure can be started only by successively moving the substrate to each exposure angle of view and adjusting the inclination without retracting the substrate from the original. As a result, the exposure cycle time can be reduced, and the throughput can be greatly improved.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

[0020] Figure 1 shows a main portion of a proximity exposure apparatus according to an embodiment, which is a substrate holding means for holding each of the mask M ₁ is a wafer W ₁ and the original is a substrate each other close to An X-ray proximity exposure apparatus comprising: a wafer stage 1 as a mask, a mask stage 2 as an original holding means, and an alignment optical system 3 for measuring a distance between the wafer W ₁ and the mask M ₁ and a displacement between the two. The wafer stage 1, the mask stage 2, the alignment optical system 3, and the like are supported by a support 5 supported in the exposure chamber 4 via a vibration isolator 4a.

An X-ray L _1, which is a charged particle storage ring radiation emitted from a light source (not shown), is introduced into the exposure chamber 4 through a beam duct 6 controlled to a high vacuum, and
Exposing the wafer W ₁ through _1. The exposure chamber 4 is controlled to a reduced pressure atmosphere of helium gas, and a beryllium window 7 is provided between the exposure chamber 4 and a high vacuum beam duct 6 for shutting off both atmospheres.

The X-rays L ₁ introduced from the beam duct 6 into the exposure chamber 4 through the beryllium window 7 are magnified by a magnifying mirror (not shown) and have an intensity distribution in the vertical direction (Y-axis direction). in order, exposure unevenness is generated in the wafer W _1. Therefore, the shutter 8 is disposed upstream of the mask M _1, to adjust the exposure time by controlling the moving speed of the shutter 8 by the drive unit 8a, is configured so as to eliminate exposure nonuniformity.

The wafer stage 1, a wafer chuck 1 with a suction surface 10a is retaining surface for adsorbing the wafer W ₁
0 and the wafer chuck 10 via the tilt stage 20
Is provided. Tilt stage 20, the rear surface of the wafer chuck 10 has three Z drive unit 20a for each reciprocating movement of the X-ray L ₁ in the optical axis direction (Z axis direction) in the three points on the concentric circles, these driving amount If the distances are the same, the distance between the wafer W ₁ and the mask M ₁ changes, and by individually controlling the driving amount of each Z drive unit 20a, the inclination angle and the direction of the wafer W ₁ can be adjusted. It is free.

The XY stage 30 has a Y stage that can reciprocate in the Y-axis direction along a guide 30a and an X stage that can reciprocate in the X-axis direction on the Y stage. wafer W subjected to step movement for moving the exposure view angle ₁ to sequentially face the mask M ₁ exposure position, and correcting the positional deviation of the wafer W ₁ and the mask M ₁ based on the output of the alignment optical system 3 Do the role of doing.

The suction surface 10a of the wafer chuck 10 is a spherical surface finished with high precision, and has a plurality of suction grooves 10b which are concentrically arranged suction means as shown in FIG. , by evacuating by a vacuum pump connected to the piping 10c, the wafer W ₁ suction surface 1
A vacuum suction force for suctioning at 0a is generated.

The radius of curvature of the suction surface 10a of the wafer chuck 10 is 1 if the wafer W ₁ is an 8-inch wafer for example
00m. Generally the cross-section of the wafer W ₁ is a contract form, and because in the case of 8-inch wafer thickness fluctuation allowed in SEMI standard is 10μm or less, the radius of curvature of the suction surface 10a of the wafer chuck 10 is 1
If it is 00 m, the difference in height between the center and the outer periphery is 5 μm
And the wafer W ₁ is held at the suction surface 10 of the wafer chuck 10.
there is no risk that the outer peripheral portion of the exposure surface of the wafer W ₁ is higher than the center in a state of being adsorbed to a.

[0027] Therefore, if adjusting the center of the wafer W ₁ a predetermined exposure gap by the tilt stage 20, for example to 10 [mu] m, even when the wafer W ₁ is step-moved in the XY direction as such, the wafer W ₁ and the mask M There is no danger of ₁ touching. Therefore, the step of retracting the wafer from the mask when the wafer is step-moved as in the conventional example can be omitted.

When the thickness unevenness of the wafer W ₁ is random, the height difference between the center and the outer peripheral portion of the suction surface 10 a of the wafer chuck 10 is set to be equal to or more than the allowable value of the wafer thickness unevenness. The radius of curvature of the suction surface 10a must be set.

The exposure cycle for each exposure field angle of the wafer W ₁ is carried out as follows. As shown in FIG.
For example after exposing the central exposure view angle of the wafer W _1, without retracting the wafer W ₁ from the mask M _1, (b)
As shown in (5), the step is moved to the next exposure angle of view. Subsequently, as shown in (c) of FIG. 3, to adjust the inclination of the exposure surface of the wafer W ₁ (the tilt) by driving the tilt stage 20 performs the exposure in the same manner as (a).

As described above, if the exposure gap is set when exposing the exposure field angle at the center of the wafer, the step of setting the exposure gap is not required when exposing the remaining exposure field angle. The cycle time can be shortened and the throughput can be greatly improved.

As a result, the productivity of a semiconductor device or the like can be improved, and the cost can be greatly reduced.

Instead of making the chucking surface of the wafer chuck spherical, another convex shape such as a paraboloid of revolution may be used.

Next, an embodiment of a method of manufacturing a semiconductor device using the above-described exposure apparatus will be described. FIG. 4 shows a semiconductor device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel,
2 shows a flow of manufacturing a CCD, a thin-film magnetic head, a micromachine, and the like. In step S1 (circuit design), a circuit of a semiconductor device is designed. In step S2 (mask production), a mask on which the designed circuit pattern is formed is produced. On the other hand, in step S3 (wafer manufacture), a wafer as a substrate is manufactured using a material such as silicon. Step S4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next step S5
(Assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step S4.
It includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step S6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step S5 are performed. Through these steps, a semiconductor device is completed and shipped (step S7).

FIG. 5 shows a detailed flow of the wafer process. In step S11 (oxidation), the surface of the wafer is oxidized. In step S12 (CVD), an insulating film is formed on the wafer surface. In step S13 (electrode formation), electrodes are formed on the wafer by vapor deposition. Step S14
In (ion implantation), ions are implanted into the wafer. In step S15 (resist processing), a photosensitive agent is applied to the wafer. In step S16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step S17 (developing), the exposed wafer is developed. In step S18 (etching), portions other than the developed resist image are removed. In step S19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.
By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been conventionally difficult to manufacture.

[0035]

Since the present invention is configured as described above, it has the following effects.

When a substrate such as a wafer is moved in steps, troubles such as interference between the substrate and an original such as a mask can be avoided, and the throughput can be greatly improved. As a result, the productivity of semiconductor devices and the like can be improved and the cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of a proximity exposure apparatus according to one embodiment.

FIG. 2 shows a wafer chuck of the apparatus of FIG. 1;
(A) is a plan view and (b) is a sectional view.

FIG. 3 is a view for explaining a step movement of a wafer chuck in the apparatus of FIG. 1;

FIG. 4 is a flowchart showing a manufacturing process of a semiconductor device.

FIG. 5 is a flowchart showing a wafer process.

FIG. 6 is a schematic sectional view showing a main part of one conventional example.

FIG. 7 is a view illustrating a step movement of a wafer chuck in the apparatus of FIG. 6;

[Description of Signs] 1 wafer stage 2 mask stage 3 alignment optical system 4 exposure chamber 6 beam duct 8 shutter 10 wafer chuck 20 tilt stage 30 XY stage

Claims (5)

[Claims] 1. An apparatus comprising: an original holding means for holding an original; a substrate holding means having a holding surface for adsorbing a substrate; and a driving means for moving the substrate holding means to position the substrate with respect to the original. Wherein the holding surface of the substrate holding means has a convex shape protruding toward the master. 2. The proximity exposure apparatus according to claim 1, wherein the holding surface is a spherical surface. 3. The proximity exposure apparatus according to claim 1, wherein a difference in height between the center and the outer peripheral portion of the holding surface is equal to or more than an allowable value of uneven thickness of the substrate. 4. The apparatus according to claim 1, wherein the holding surface has a concentric suction means for sucking the substrate.
The proximity exposure apparatus according to claim 1. 5. The proximity exposure apparatus according to claim 1, wherein the proximity exposure apparatus is an X-ray proximity exposure apparatus that uses X-rays as exposure light.