JPH07153664A - Mask holding device and aligner using it as well as manufacture of device - Google Patents

Abstract

PURPOSE:To hold a mask in an X-ray exposure operation in the substantially same state as in an EB drawing operation to manufacture the mask by s method wherein means which generate a force to pull the mask to the side of a mask- chuck holding face are installed so as to correspond to three point support positions. CONSTITUTION:A mask chuck 11 is installed on an aligner body. Coupling holes 12 are made in three places which correspond to a conical-hole part 5, a V-groove part 6 and a plane part 7, and balls 10 are fixed to the holes. When a mask is attached to the mask chuck 11, the center of every ball 10 and the center of a magnetic ring 8 are made to coincide on the same normal line. Four each of electromagnet units 13 in a total of 12 units are arranged around the circumference of the three balls 10 so as to be symmetric with respect to an axis. Then, a line of magnetic force which passes the magnetic ring 8 on the side of the mask from a yoke on one side and which is circulated via a yoke on the other side is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for holding a mask used in an exposure apparatus or the like.

[0002]

2. Description of the Related Art In recent years, the degree of integration of semiconductor integrated circuits has become higher and higher, and the semiconductor manufacturing equipment for manufacturing them has a higher printing line width due to the higher integration density. Exposure accuracy is required. To make the printing line width narrower, it is effective to shorten the wavelength of the light source used for exposure. Therefore, development of an X-ray exposure apparatus using X-rays having a wavelength shorter than that of ultraviolet light, which is generally used at present, is underway.

FIG. 11 schematically shows an X-ray mask and a mask chuck mounted on a conventional proximity gap type X-ray exposure apparatus. FIG. 11A shows an X-ray mask. Reference numeral 100 is a reinforcing mask frame, 101 is a mask substrate made of silicon, 102 is an inorganic film (mask membrane) formed by removing a part of the mask substrate by back etching, and 103 is an EB drawing device or the like on the mask membrane. It is a transfer pattern of a semiconductor circuit or the like formed by drawing. Reference numeral 105 denotes a magnetic ring made of a magnetic material, which is embedded in the mask support frame 1. Figure 1
Reference numeral 1 (b) shows a magnetic chuck type mask chuck. 11
0 is a ring-shaped chuck base, and the inside is an exposure X
A hole 111 through which the wire passes is provided. A magnetic unit 112 is circumferentially arranged corresponding to the magnetic ring 105 and generates a magnetic force sufficient to attract and hold the X-ray mask. In this structure, the mask frame 100 of the X-ray mask is magnetically attracted and held by the holding surface of the chuck base 110 by surface contact. In addition to this magnetic attraction method, there is also a vacuum attraction method. In that case, a vacuum port is used instead of the magnetic unit, and the mask frame and the chuck base are brought into surface contact with each other by a vacuum force to be attracted and held.

However, these adsorption holding methods are
Since the mask frame 100 and the chuck base 110 are in surface contact with each other, it is necessary to finish the contact surfaces between them with high flatness. If the transfer pattern is formed by the EB drawing device during mask fabrication, the mask frame 100
If there is a slight distortion such as a warp on the suction surface of the mask frame 100, the warp of the mask frame 100 is corrected and the mask frame 100 is deformed when the mask frame 100 is held by the chuck base 110 of the X-ray exposure apparatus. 101 is transmitted to the transfer pattern 103 through the mask membrane 102, and the transfer pattern 103 may be distorted with respect to the time of drawing. The thickness of the mask membrane 102 on which the transfer pattern 103 is formed is about 2 μm and is several mm.
Compared with the thick mask substrate 101 and the mask frame 100, the rigidity thereof is very small. Therefore, the mask substrate 1
01 and the distortion of the mask frame 100 have a great influence on the mask membrane 102 and also cause a large distortion on the transfer pattern. This can be said to be a problem peculiar to a mask in which a transfer pattern is formed on an ultrathin mask membrane.

As a method of solving this, when the mask is chucked by the mask chuck, the X-ray mask is not deformed by the holding force, in other words, the mask frame is held while maintaining the distorted state at the time of pattern formation. A method of doing so (hereinafter referred to as a kinematic mount) has been proposed.

FIG. 12 shows an example of a kinematic mount. FIG. 12A shows an X-ray mask for a kinematic mount. Reference numeral 117 is a conical (funnel-shaped) hole portion, 118 is a flat surface portion, and 119 is a V groove portion in which a linear cut groove is formed along the X direction in the drawing, and these are formed on the holding surface of the mask frame 100. Has been done. 12
(B) shows a mask chuck for a kinematic mount. On the holding surface of the chuck base 110, spherical protrusions 120 that engage with the conical hole portion 117, the flat surface portion 118, and the V groove portion 119 of the mask are provided at three locations. Further, a clamp mechanism 115 for mechanically pressing and holding the mask at three points is provided.

In this structure, the holding state shown below is established and the six degrees of freedom of the mask are positioned without being excessively constrained.

[0008] According to this kinematic mount, an external force that deforms the mask frame 100 hardly acts when holding the mask during exposure, and the mask can be held (strain-free) in the same state as when the mask pattern is formed by the EB drawing device. The feature is that pattern distortion due to deformation of the mask support frame can be suppressed.

[0009]

However, in the above example of the kinematic mount, the clamp mechanism 11 is used.
5 is provided on the side of the wafer that closely faces the mask, that is, on the proximity gap side. In order to prevent the clamp mechanism from touching the wafer, the cross-sectional thickness of the portion where the transfer pattern of the mask is formed is defined as the sum of the cross-sectional thickness of the clamp mechanism and the cross-sectional thickness of the portion to be clamped of the mask fume. It has to be big.

Particularly, in the vertical type X-ray exposure apparatus, the mask must be held vertically on the mask chuck, and for this purpose, a clamping mechanism generates a sufficient clamping force to overcome gravity. There is a need. Therefore, it is difficult to design the clamp mechanism to be thin, and it is difficult to make the mask thin.

That is, the strong clamping force and the thin mask are not compatible. In addition, the sequence and the fail-safe mechanism for preventing the wafer from contacting the clamp mechanism are complicated.

Accordingly, in the proximity gap type X-ray exposure apparatus, the method of holding and holding the mask by a mechanical clamp mechanism is not preferable, in spite of the EB exposure apparatus which does not have the special situation of proximity gap.

The present invention is to solve the above problems,
In three-point support chucking such as kinematic mount method, mask holding during X-ray exposure can be made substantially the same as that during EB drawing during mask making without using a mechanical clamping mechanism. Another object of the present invention is to provide a mask holding device, an exposure device using the same, a device manufacturing method, and the like.

[0014]

According to one mode of the present invention for solving the above problems, in a mask holding device for supporting an exposure mask on a mask chuck holding surface at three positions, the mask is pulled toward the mask chuck holding surface. The mask holding device is characterized in that means for generating force are provided respectively corresponding to the three positions. Here, the means for generating the force is a magnetic attraction mechanism provided on the mask chuck holding surface corresponding to the three positions, or a vacuum attraction mechanism provided on the mask chuck holding surface corresponding to the three positions. preferable.

[0015]

【Example】

<First Embodiment> A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a mask chuck of an X-ray exposure apparatus with an X-ray mask attached, FIG. 2 is a detailed view of a magnet chuck, and FIG. 3 is a state in which the mask is attached to an EB drawing apparatus.

In FIG. 1, the X-ray mask has a transfer pattern 4 made of gold or the like (a mask substrate (silicon wafer) 3 with a mask membrane (inorganic film) 2).
Is bonded to the surface of the mask frame 1. Further, on the back surface of the mask frame 1, the same conical hole portion 5, the V groove portion 6, and the flat surface portion 7 for contacting the three spheres 10 provided on the mask chuck similar to those described in the above conventional example. Is provided. A ring-shaped groove 9 for mounting the ring-shaped magnetic ring 8 is provided around them along with a relief groove for processing. As described below, E
When the X-ray mask is produced by the B drawing device, the magnetic ring 8
However, when fixing the completed X-ray mask to the mask chuck of the exposure apparatus, the magnetic ring 8 is attached to the mask by adhesion or the like. As a material for the magnetic ring 8, a magnetic material such as stainless steel is used.

On the other hand, the mask chuck 1 is provided on the main body of the exposure apparatus.
1 is provided. Engagement holes 12 are provided on the surface of the mask chuck 11 at three positions corresponding to the conical hole portion, the V groove portion, and the flat surface portion, and three balls 10 are fixed thereto. When the mask is mounted on the mask chuck 11, the center of the sphere 10 and the center of the magnetic ring 8 are aligned on the same normal line. Further, the protruding height of each sphere 10 with respect to the chuck surface 11 is adjusted so that the surface of the mask chuck 11 and the lower surface of the mask frame 1 are parallel to each other. This is achieved by making the sizes of the engagement holes 12 different or the sizes of the balls 10 themselves different.

As a modification, instead of a sphere, a protrusion having a spherical tip may be fixed to the engaging hole 12. In addition, in this embodiment, three balls are placed on the mask chuck side, a conical hole portion,
Although the V groove portion and the flat surface portion are provided on the mask frame side, they may be reversed. Further, the portions engaging with the three balls do not necessarily have to be a combination of a conical hole portion, a V groove portion, and a flat surface portion, and may be all conical hole portions or all V groove portions, for example. These modified examples are not limited to the present embodiment, and can be similarly applied to the second and subsequent embodiments described later.

Around each of the three balls 10, four electromagnet units 13 are arranged axially symmetrically, 12 in total. Details of the electromagnet unit 13 are shown in FIG. Each unit has a permanent magnet 14, a coil 15,
It consists of a yoke 16. The permanent magnets 14 are magnetized in the thickness direction, and generate magnetic lines of force that pass from one yoke 16 through the magnetic ring 8 on the mask side and circulate through the other yoke. The coil 15 is wound so that the normal line of the plane portion where the current loop exists coincides with the direction of the magnetic force line.

The fabrication of the X-ray mask, after passing through steps such as SiC membrane vapor deposition, back etching and mask frame adhesion, is mounted on the mask chuck 20 of the EB drawing apparatus as shown in FIG. 3 and patterned by the electron beam 25. Is done. The mask chuck 20 is provided with an engagement hole 21 having a positional relationship similar to that provided in the mask chuck of the X-ray exposure apparatus described above, and three balls 22 are fixed thereto. Corresponding to these balls 22, three sets of clamp arms 23 for holding the mask are provided. Each arm 23 is configured to push the center of the corresponding ball 22.

In order to fix the X-ray mask to the EB drawing device in the mask manufacturing, the conical hole portion 5, the V groove portion 6 and the flat surface portion 7 of the mask frame are brought into contact with the three spheres 22 of the mask chuck 20, respectively. After positioning, it is clamped by three sets of arms 23. The vector of each clamping force is
It has a direction passing through the center of each sphere 22 and perpendicular to the pattern surface.
The pattern is not distorted because it is a kinematic mount. When the mask pattern formation is completed in this way, the magnetic ring 8 is attached to the magnetic ring attachment surface of the ring-shaped groove 9 of the mask frame 1 by an adhesive or the like to complete the mask. When the X-ray mask is mounted on the X-ray exposure apparatus, the magnetic ring 8 is attached while being finely adjusted by a jig so as to face the yoke of the mask chuck with a gap of about several tens of μm.

The procedure for mounting the completed mask on the X-ray exposure apparatus will be described below. First, an electric current is applied to the coil 15 of the electromagnet unit 13 of the mask chuck 11 of the X-ray exposure apparatus in such a direction as to cancel the magnetic lines of force of the permanent magnet 14. At this time, the electromagnet unit 13 of the chuck exerts no force even if the magnetic ring 8 faces the yoke 16 with a minute gap. Next, the conical hole portion 5, the V groove portion 6, and the flat surface portion 7 of the mask frame 1 are brought into contact with the three balls 10 on the mask chuck with a mask hand (not shown), and then,
The coil 15 of the electromagnet unit 13 is deenergized. Then, the magnetic lines of the permanent magnets cause the three magnetic rings 8 to move to the yoke 1.
6 is pulled toward the mask chuck side while maintaining a small gap with the surface of 6, and the X-ray mask is fixed with the three balls 10 as a mechanical reference. Since the sphere 10 is located at the center of the magnetic ring 8 and the electromagnet units 13 around each sphere 10 are arranged in axial symmetry, the resultant vector of the tensile force applied to the magnetic ring 8 is shown. Is a direction that passes through the center of the sphere 10 and is perpendicular to the chuck surface. Therefore, comparing the time when the X-ray mask is fixed on the X-ray exposure device and the time when it is fixed on the EB drawing device, both the mechanical reference of positioning, the position and direction of the holding force vector are The same mask can be held and fixed in the same state. As a result, pattern distortion does not occur between EB writing and X-ray exposure, and exposure transfer can be performed with high accuracy.

<Embodiment 2> Some of the modifications of the above embodiment are shown below. 4 and 5 show a second embodiment. The difference from the above-described embodiment is that the attachment of the magnetic ring to the mask involves three indirect members 17.
The same reference numerals as in the previous embodiment represent the same members.

There are three types of indirect members 17, each of which has a conical hole portion, a V groove portion, and a flat surface portion, which are provided on the chuck side and are in contact with a sphere. Each indirect member 17 is provided with a mounting reference surface finished with high precision by grinding or the like, and four female screw portions for mounting the magnetic ring 18. The magnetic ring 18 is provided with a counterbore for a screw, and a screw 19 is inserted therein to screw the magnetic ring 18 to the indirect member 17 at four positions. The indirect member 17 is made of non-magnetic metal such as non-magnetic stainless steel, and the magnetic ring 18 is made of magnetic stainless steel. Also, the magnetic ring 18
The position of the screw is provided at a position opposed to the yoke of the electromagnet unit of the mask chuck, which is opposed to the X-ray exposure apparatus when fixed, so that the magnetic lines of force of the permanent magnet of the electromagnet unit are not reduced.

Similar to the previous embodiment, when fixing to the EB drawing device (FIG. 5), mechanically clamping the X-ray mask without a magnetic ring, and fixing to the X-ray exposure device (FIG. 4). The magnetic ring is attached and clamped by magnetic force, and the clamping force of both is the same vector position and direction.

The present embodiment further has the advantage that the magnetic ring can be removed at any time. In the previous embodiment, once the mask is completed, it cannot be mounted on the EB-related device again, but in this embodiment, the magnetic ring is screwed, and by removing this, it can be mounted on the EB-related device even after the mask is completed. It is possible. This is effective when measuring the mask patterning accuracy with an EB length measuring machine or the like.

Furthermore, according to the present embodiment, even if a strain is generated near the magnetic ring due to magnetic attraction when the device is fixed to the X-ray exposure apparatus, this strain is absorbed by the indirect member,
The mask frame and the transfer pattern are not distorted.

<Third Embodiment> FIGS. 6 and 7 show a third embodiment. Although the magnetic adsorption method has been used in the above-mentioned embodiments, this embodiment is characterized in that the vacuum adsorption method is adopted.
The same reference numerals as those used in the above embodiments represent the same members.

In FIG. 6, three indirect members 30 are attached to the back surface of the mask frame 1 of the X-ray mask, and each of them has a conical hole portion, a V groove portion, and a flat surface portion formed on the bottom surface, as in FIG. Has been done. A sealing member 31 is fixed around each indirect member 30. The material of the indirect member 30 may be either metal or non-metal, and the material of the seal member 31 is soft and highly airtight.

On the other hand, a ring-shaped vacuum suction groove 32 is provided around each of the three spheres 10 fixed to the mask chuck surface of the X-ray exposure apparatus.
It is connected to a vacuum pump 34 via a vacuum pump and supplies a vacuum to the suction groove 32.

FIG. 7 is a diagram for explaining the mounting of the mask on the EB drawing apparatus. Mechanical clamping by the clamping arm 23 is the same as in FIGS. 3 and 5 described above. An escape groove 35 is provided on the surface of the mask chuck 20 at a position where the seal member 31 comes. This is to prevent a vacuum region from being formed by the indirect member 30 of the mask, the seal member 31, and the chuck surface of the EB drawing device.

The procedure for mounting the X-ray mask produced by the EB drawing apparatus on the mask chuck of the X-ray exposure apparatus will be described below. First, the suction groove 32 is set to the atmosphere in which the X-ray exposure apparatus is placed, for example, the same atmosphere as He of 150 Torr. Then, the three balls 10 are positioned by a mask hand (not shown) so that the conical hole portion, the V groove portion, and the flat surface portion provided in each indirect member 30 come into contact with each other. After positioning, the vacuum pump 34 is operated to apply a vacuum to each suction groove 32.
Then, around each sphere 10, the indirect member 30 and the seal member 3 are provided.
1. A vacuum region is formed by the surface of the mask chuck 20, and a tensile force that pulls the indirect member 30 toward the mask chuck is generated due to the pressure difference from the ambient atmospheric pressure. In this way, the X-ray mask is fixed with the three balls 10 as a mechanical reference. Here, the sphere 10 is placed at the center of the ring-shaped vacuum suction groove 32.
Is placed, the vector of the tensile force applied to the indirect member 30 passes through the center of the sphere 10 and is perpendicular to the pattern surface. Therefore, as in the previous embodiment,
When the X-ray mask is fixed on the X-ray exposure device,
When compared with the case where the mask is fixed on the drawing apparatus, the mechanical reference for positioning, the position and direction of the holding force vector are the same, and the mask can be held and fixed in the same state. As a result, pattern distortion does not occur between EB writing and X-ray exposure, and exposure transfer can be performed with high accuracy.

<Embodiment 4> Next, an embodiment of an exposure apparatus for manufacturing a microdevice (semiconductor device, thin film magnetic head, micromachine, etc.) using the mask and mask chuck described above will be described. FIG. 8 is a view showing the arrangement of the X-ray exposure apparatus according to this embodiment. In the figure, a sheet beam-shaped synchrotron radiation 31 emitted from the SR radiation source 30 is
The convex mirror 32 magnifies the emitted light in a direction perpendicular to the orbital surface. The radiated light reflected and expanded by the convex mirror 32 is adjusted by the shutter 33 so that the exposure amount in the irradiation area becomes uniform, and the radiated light passing through the shutter 33 is guided to the X-ray mask 34. The X-ray mask 34 is held by a mask chuck (not shown) by the mounting method as described above. The exposure pattern formed on the X-ray mask 34 is exposed and transferred onto the wafer 35 by a step & repeat method or a scanning method.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. Fig. 9 shows microdevices (semiconductor chips such as IC and LSI, liquid crystal panels, CC
D, thin film magnetic head, micromachine, etc.). In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. 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 the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step 6 (inspection), an operation confirmation test of the semiconductor device manufactured in step 5,
Conduct inspections such as durability tests. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 10 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed 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 difficult to manufacture in the past.

[0036]

According to the present invention, the mask can be chucked to the X-ray exposure apparatus in substantially the same state as the mechanical clamp to the EB drawing apparatus at the time of mask production without using a mechanical clamp mechanism. Since it is not necessary to provide a clamp mechanism on the wafer side, the mask can be made thinner.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an X-ray exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed view of the magnetic unit of the first embodiment.

FIG. 3 is a configuration diagram of an EB drawing apparatus according to a first embodiment.

FIG. 4 is a configuration diagram of an X-ray exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of an EB drawing apparatus according to a second embodiment.

FIG. 6 is a configuration diagram of an X-ray exposure apparatus according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of an EB drawing apparatus according to a third embodiment.

FIG. 8 is an overall view showing an embodiment of an X-ray exposure apparatus.

FIG. 9 is a diagram showing a flow of a device manufacturing method.

FIG. 10 is a diagram showing a detailed flow of a wafer process.

FIG. 11 is a diagram illustrating a conventional magnetic chuck type mask chuck.

FIG. 12 is a diagram illustrating a conventional kinematic mount type mask chuck.

[Explanation of symbols]

 1 Mask Frame 2 Mask Membrane 3 Mask Substrate 4 Transfer Pattern 5 Conical Hole 6 V Groove 7 Plane 8 Magnetic Ring 9 Ring-shaped Groove 10 Sphere 11 Mask Chuck (X-Ray Exposure Device Side) 12 Engagement Hole 13 Magnetic Unit 14 Permanent Magnet 15 Magnetic coil 16 Yoke 20 Mask chuck (EB exposure device side) 21 Engagement hole 22 Sphere 23 Clamping arm

Claims (7)

[Claims] 1. In a mask holding device for supporting an exposure mask on a mask chuck holding surface at three positions, a means for generating a force for pulling the mask toward the mask chuck holding surface is provided corresponding to each of the three positions. A mask holding device characterized by being provided. 2. The mask holding device according to claim 1, wherein the means for generating the force has a magnetic attraction mechanism provided on the mask chuck holding surface corresponding to the three positions. 3. The mask holding device according to claim 1, wherein the means for generating the force has a vacuum suction mechanism provided on the mask chuck holding surface corresponding to the three positions. 4. The mask holding device according to claim 1, wherein the mask is a mask for X-ray exposure. 5. An exposure apparatus comprising: the mask holding device according to claim 1; and an exposure means for exposing and transferring a transfer pattern of a mask held by the mask holding device onto a wafer. 6. The exposure apparatus according to claim 5, wherein said exposure means performs exposure with X-rays. 7. A device manufacturing method, comprising a step of manufacturing a device using the dew air conditioner according to claim 5.