JPH10242032A - Mask retainer, aligner, device manufacturing method and mask structure body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly precisely correct the transfer magnification and the like of a mask pattern by a simple method, by applying a load to a ring type frame of a mask structure body, from the direction wherein the diagonal line of a rectangular window with a mask pattern is extended. SOLUTION: A rectangular window 12 of a square which is a radiation beam transmission region is formed in the central part of a circular mask substrate 11 composed of a silicon wafer. The mask substrate 11 is bonded to a ring type retaining frame 13 for retaining and reinforcing the mask substrate 11, in the following positional relation. That is, the frame rigidity in the direction wherein the diagonal line of the rectangular window 12 is extended to the direction of the rectangular window 12 becomes larger than the frame rigidity in the direction wherein the direction which passes the center and is in parallel to each side of the rectangle is extended. Hence loads P1 , P2 (P1 =P2 =P) are given toward the mask center from the respective directions wherein the diagonal lines of the rectangular window 12 of the square of the mask substrate 11 are extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask structure used in an exposure apparatus using radiation such as a radiation beam such as X-rays, vacuum ultraviolet rays or electron beams, and a technique for correcting the pattern.

[0002]

2. Description of the Related Art In recent years, circuit patterns have been miniaturized in order to improve the integration degree and operation speed of semiconductor devices such as LSIs. In circuit pattern formation in the process of manufacturing these LSIs, attention has been paid to formation of a fine pattern by a lithography technique using a radiation beam such as X-ray, vacuum ultraviolet ray, or electron beam. As one of the powerful methods, there is a method in which a mask and a wafer are arranged close to each other and irradiated with a radiation beam so as to perform the same-size exposure transfer.

[0003] In this method, since the mask and the wafer are placed in close proximity to each other and transferred at the same magnification, it is difficult to adjust the transfer magnification of the mask pattern transferred to the wafer.
One method for achieving this is disclosed in Japanese Patent Laid-Open No. 60-182.
The X-ray exposure apparatus disclosed in Japanese Patent No. 441 proposes a method of controlling the pattern magnification on the membrane by positively deforming the mask substrate by applying a force to the mask substrate from the outside by a pressing mechanism. I have.

[0004]

However, in the prior art described in the above publication, the mask is clamped at three locations around the frame of the mask and these are relatively moved to deform the mask frame. Therefore, it is practically difficult to correct a desired mask pattern, particularly to correct an XY isotropic magnification.

The present invention has been made to further improve the above-mentioned prior art, and is an apparatus, a method, and a mask structure capable of correcting a mask pattern transfer magnification and the like with high accuracy while using a simple method. The purpose is to provide such.

[0006]

According to the present invention, there is provided a mask structure having a mask substrate provided with a rectangular window provided with a mask pattern and a ring-shaped frame. It has a chuck mechanism and a mechanism for applying a load to the frame from a direction in which a diagonal line of the rectangular window is extended.

[0007] Preferably, the mechanism for applying the load is 2
It has two pressing mechanisms for pressing the frame from two diagonal directions.

Preferably, in the frame, diagonal rigidity of the rectangular pattern is relatively large as compared with other directions.

Preferably, the chuck mechanism has a chuck mechanism for chucking the frame at three positions in a direction perpendicular to the pattern surface. More preferably, the three positions are arranged in a regular triangular shape, and when the mask structure is held by the chuck mechanism, one of the three extends from the center of the rectangular window in a direction parallel to the side of the rectangle. It is located in the direction.

An exposure apparatus according to the present invention includes the above-described mask holding apparatus, and exposes a mask held by the mask holding apparatus.

The device manufacturing method according to the present invention comprises the steps of preparing a mask substrate having a rectangular window on which a mask pattern is formed, a mask structure having a ring-shaped frame and a wafer, and forming a diagonal line of the rectangular window. Correcting the mask pattern by applying a load to the frame from an extended direction, and transferring the mask pattern to the wafer by irradiating exposure energy while holding the mask structure and the wafer in a close proximity to each other It has a step.

Another aspect of the device manufacturing method of the present invention is as follows.
It has a mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame, and the frame has a structure in which the diagonal rigidity of the rectangular window is relatively large compared to other directions. Preparing a proper mask structure and a wafer, correcting the mask pattern by applying a load to the frame, and irradiating exposure energy while holding the mask structure and the wafer in a positional relationship close to each other. A step of transferring a mask pattern onto the wafer.

[0013] Preferably, the exposure energy is a radiation beam such as X-ray, vacuum ultraviolet ray or electron beam.

The mask structure of the present invention has a mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame. The frame has a diagonal rigidity of the rectangular window in another direction. It is characterized in that it is relatively large as compared with.

[0015] Preferably, the mask structure is a mask structure for lithography using a radiation beam such as X-rays, vacuum ultraviolet rays or electron beams.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

<Mask Structure and Retention Correction Method Thereof> FIG. 1 is a diagram showing a configuration of a transmission mask structure used for lithography using a radiation beam such as X-ray, vacuum ultraviolet ray, or electron beam. In the figure, reference numeral 11 denotes a circular mask substrate made of a silicon wafer, in which an orifice portion which is a cutout for defining a rotation direction is formed, and a square rectangular window 12 which is a radiation beam transmitting region is formed in the center of the substrate. Is provided. This mask substrate is prepared by forming a SiN
After forming the SiC film or the SiC film, only the portion that becomes a rectangular window from one side of the Si substrate is removed by back etching, leaving only the SiN or SiC film, which is an extremely thin membrane. A mask pattern to be transferred with a radiation absorber (metal such as W or Ta) is formed on the membrane. As will be described later, the mask pattern is formed at a slightly larger magnification in advance than the ideal transfer pattern size. The offset magnification is determined in consideration of the process distortion assumed in the wafer process after the transfer.

Reference numeral 13 denotes a ring-shaped support frame for supporting and reinforcing the mask substrate. Support frame 13
Is preferably heat resistant glass or ceramics such as SiC. Although FIG. 1 is an exploded view in which the mask substrate 11 and the support frame 13 are exploded in order to explain the shape of the support frame, it is actually a structure in which these are joined. A portion indicated by a hatched portion 14 on the upper surface of the support frame 13 is a bonding position with the mask substrate 11, and is bonded by a method such as adhesive bonding or anodic bonding.

As shown in FIG. 1, the support frame 13 has a ring shape such that the outer periphery is circular and the inner periphery is octagonal, and the frame rigidity varies depending on the direction from the center. With respect to the direction of the rectangular window 12 of the mask substrate 11 joined to the support frame 13, the frame rigidity (frame cross-sectional area) in the direction in which the diagonal line of the rectangular window is extended is
The two are joined in a positional relationship such that it is greater than the frame rigidity (frame cross-sectional area) in the direction extending through the center and parallel to each side of the rectangle.

FIG. 2 is a view for explaining the relationship between the direction in which a load is applied to the support frame and the rectangular window when performing magnification correction while holding the mask structure. Loads P ₁ and P ₂ (P ₁ = P ₂ = P) are applied toward the center of the mask from directions in which the diagonal lines of the square rectangular windows of the mask substrate are extended. Further, since two abutment fixing members 15 are arranged at respective opposing positions in which the vector directions of these additional loads are extended, a reaction force (P) is applied to the support frame 13 from each fixing member 15 toward the mask center. Given. As a result, a force is applied to the outer periphery of the support frame 14 from four directions in which the two diagonal lines of the rectangular window are extended.

FIG. 3 is a vector diagram showing the pattern displacement of the membrane of the rectangular window as a result of applying a load as shown in FIG. 2. As shown in FIG. 3, the mask pattern shows a substantially isotropic displacement. . That is, the diagonal direction of the rectangular window of the mask substrate 11 where the rigidity is small is reinforced by the high rigidity portion of the support frame 13, and the horizontal and vertical directions where the rigidity of the mask substrate is large are strengthened by the low rigidity portion of the support frame. , An overall isotropic pattern displacement (magnification reduction) can be obtained. If the additional loads P1 and P2 are made different, it is also possible to reduce the magnification anisotropically.

Here, as a comparative example, a load is applied not from the diagonal direction of the rectangular window but from the side direction using a support frame having uniform rigidity in both directions from the center (the outer periphery and the inner periphery are circular). Will be described. As shown in FIG. 4, a load is applied to the sides of the square rectangular window from the vertical and horizontal directions toward the center of the mask. Then, as shown by the vector diagram in FIG. 5, the displacement at the diagonal position outside the rectangular pattern is small, and the horizontal and vertical positions from the center are relatively largely displaced, indicating a pincushion-shaped deformation. That is, as compared with the isotropic uniform reduction as shown in FIG. 3, the reduction becomes distorted, and the pattern distortion increases.

In this embodiment, (1) a load is applied to the outer periphery of the support frame from a direction in which the diagonal line of the rectangular window of the mask substrate is extended, and (2) the support frame has another rigidity in the diagonal direction of the rectangular window. The use of a mask that is relatively large compared to the direction allows the best magnification correction with the least distortion due to the synergistic effect of the combination of the two. Since the magnification correction is better than that of FIGS. 4 and 5, the shape of the support frame may be a ring shape having uniform rigidity in all directions as shown in FIG.

Next, the structure and operation of a mask holding device for holding the mask structure in the exposure apparatus will be described with reference to FIGS. FIG. 6 shows a non-holding state of the mask structure, and FIG. 7 shows a holding state.

The mask chuck 61 is placed on the base plate 612.
3, the base plate 612 and the mask chuck 6
Holes 614 are provided at positions where the thirteen exposure radiation beams pass. The mask chuck 613 is provided with a block 601 where the mask structure is abutted and positioned.
Block 601 includes two mutually orthogonal butting surfaces that contact the support frame of the mask structure at two points when viewed from above. On the base plate 612, three projections 602, 60 having spherical ends are provided for supporting the mask.
3, 604 are formed, and three rotary arms 605, 606, 607 corresponding to these are provided. A projection is also formed at the tip of each arm. The positions of these three projections are arranged in an equilateral triangle, and when the mask structure is held by the chuck mechanism, one of the three extends from the center of the rectangular window in a direction parallel to the side of the rectangle. Located in.

The base plate 612 is provided with two rotatable load units 608 and 609 for applying loads to the outer periphery of the mask support frame from two directions.
Each load unit includes a rod, a detector (load cell) for detecting a reaction force when a load is applied by the rod, and an actuator for rotating the load unit itself.

In the above configuration, the mask structure 100 transferred by the transfer arm (not shown) is
And XY horizontal positioning is performed. And the mask chuck projection 60
The back surface of the mask structure 100 is supported at three points of 2, 603, and 604, and the three arms 605, 606, and 607 rotate to sandwich the mask frame from above and below at three places, thereby allowing the mask to move in the YYZ directions. All positioning is completed. At this time, the protrusion of the arm 605 is
No. 00 is engaged with the V-groove 105 formed on the upper surface of the frame so that there is no shift in the rotation direction.

Next, the load units 608 and 609 are rotated in the mask direction, and the tips of the rods 610 and 611 of each load unit are abutted against the support frame of the mask structure as shown in FIG. At this time, each rod 61 contacting
Reference numerals 0 and 611 apply loads toward the center of the mask, and the directions in which the loads are applied are orthogonal to each other. As a result, a load is applied to the outer periphery of the support frame of the mask from four directions in which the diagonal lines of the rectangular windows of the mask are extended.

The drawing dimension of the mask pattern of the mask structure 100 is drawn larger than a predetermined design dimension by a specified displacement for magnification correction. Prior to exposure, the magnification of the mask and the wafer pattern is measured by an alignment measurement system provided in the exposure apparatus, and a set load applied to the mask is determined so as to perform necessary magnification correction. The setting of the load utilizes the relationship between the mask pattern displacement and the set load applied to the mask, which is obtained in advance in the control device and stored in the control device as a data table or conversion formula. Next, a voltage is applied to the actuator so that the load detected by the load cell becomes the set load. By performing servo control for driving the actuator based on the output of the load cell, a constant amount of load can always be applied to the mask structure even if the mask moves minutely. Further, if this servo control is always performed during the exposure, it is possible to correct the thermal distortion caused by the exposure beam, including the change in the pattern magnification.

<Modifications of Mask Structure> Next, several modifications of the mask structure will be described. In any of the examples, the support is provided from the direction in which the diagonal line of the rectangular window on which the mask pattern is formed is extended. It is characterized in that a load is applied to the frame. Further, a mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped support frame for reinforcing the mask substrate,
The support frame is characterized in that the rigidity in the diagonal direction of the rectangular window is relatively large as compared with other directions. The mechanism for applying a load while holding the mask is the same as that described with reference to FIGS. 6 and 7, and a description thereof will not be repeated.

FIGS. 8 and 9 show a modification of the mask structure. The ring-shaped support frame 23 is provided with four protrusions 24 on four sides extending in a diagonal direction with respect to the square rectangular window 11 of the mask substrate 12. The upper surfaces of these projections 24 are the bonding surfaces with the mask substrate.

FIGS. 10 and 11 show still another example of the mask structure. In this example, the support frame shape has a plurality of large and small holes 35 uniformly formed in four rectangular horizontal and vertical directions with respect to the square rectangular window 11 of the mask substrate to be joined. The number and arrangement of holes and the hole shape are not limited to this example,
The rigidity of the frame in the diagonal extension direction may be relatively large as compared with the other directions in relation to the rectangular window of the mask substrate.

FIGS. 12 and 13 show still another example of the mask structure. 4 independent of the support frame 43
The two island portions 45 are supported by a leaf spring 46. The upper surface 44 of the island portion is a bonding surface with the mask substrate. This island portion 45 is located in the diagonally extending direction of the rectangular window of the mask substrate. Further, four small holes 47 penetrating toward the center of the mask are formed in the side surface 43 on the outer periphery of the frame.

For magnification correction, as shown in FIG. 13, a rod member having a spherical tip is inserted into the four small holes 47, and a load P is uniformly applied to each of the four rod members. In this example, since a load can be applied to the mask substrate independently of the outer periphery of the frame, pattern distortion does not occur when the frame is chucked, so that more accurate magnification correction can be performed.

<Exposure Apparatus> FIG. 14 is an overall structural view of an exposure apparatus having the above-mentioned mask holding mechanism for manufacturing a semiconductor device. Here, an example of an exposure apparatus using a synchrotron as a light source is shown, but the light source may be an electron beam radiation source.

The radiation beam of high-brightness X-rays or vacuum ultraviolet rays emitted from the synchrotron ring 50 is expanded and directed to an exposure apparatus by a total reflection mirror 51. Exposure amount control is performed by the shutter 52. The radiation beam that has passed through the shutter 52 is applied to the mask structure 53, and the mask pattern is exposed and transferred to the wafer 54. The structure of the mask structure 53 and the holding correction method are as described in the above embodiment.

<Device Manufacturing Method> FIG. 15 shows a production flow of a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD) using the above exposure apparatus. In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. Step 3
In (wafer manufacture), 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 prepared mask and wafer. Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). . In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, the semiconductor device is completed,
This is shipped (step 7).

FIG. 16 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern on the mask is printed and exposed on the wafer by the above-described exposure. Step 17
In (development), the exposed wafer is developed. Step 18
In (etching), portions other than the developed resist image are scraped off. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

[0038]

According to the present invention, it is possible to provide an apparatus, a method, a mask structure, and the like, which are capable of accurately correcting the transfer magnification of a mask pattern and the like while being a simple method. In addition, if this is used, it is possible to manufacture a device with higher precision than before.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a mask structure according to a first embodiment.

FIG. 2 is a diagram showing a relationship between a load applied to the mask structure of FIG. 1 and a rectangular window.

FIG. 3 is a diagram illustrating, as a vector, a change in magnification of a mask pattern when a load is applied.

FIG. 4 is a diagram showing a comparative example.

FIG. 5 is a diagram showing a comparative example with respect to FIG. 3;

FIG. 6 is a view showing a mask holding device (non-holding state).

FIG. 7 is a view showing a mask holding device (holding state).

FIG. 8 is a diagram illustrating a mask structure according to another embodiment.

FIG. 9 is a diagram showing a relationship between a load applied to the mask structure of FIG. 8 and a rectangular window.

FIG. 10 is a diagram showing a mask structure according to another embodiment.

11 is a diagram showing a relationship between a load applied to the mask structure shown in FIG. 10 and a rectangular window.

FIG. 12 is a diagram illustrating a mask structure according to another embodiment.

13 is a diagram showing a relationship between a load applied to the mask structure of FIG. 12 and a rectangular window.

FIG. 14 is an overall schematic view of an exposure apparatus.

FIG. 15 is a diagram showing a flow of a device manufacturing process.

FIG. 16 is a diagram showing a detailed flow of a wafer process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Mask board 12 Rectangular window 13 Support frame 14 Joining part 15 Butt fixing part

Claims (11)

[Claims] 1. A chuck mechanism for holding a mask structure having a mask substrate having a ring-shaped frame and a mask substrate provided with a rectangular window on which a mask pattern is formed, and a frame extending from a direction extending a diagonal line of the rectangular window to the frame. A mask holding device having a mechanism for applying a load. 2. The mask holding apparatus according to claim 1, wherein the load applying mechanism has two pressing mechanisms for pressing the frame from two diagonal directions. 3. The mask holding device according to claim 1, wherein the frame has a rigidity in a diagonal direction of the rectangular pattern relatively larger than that in other directions. 4. The chuck mechanism according to claim 3, wherein
2. The mask holding apparatus according to claim 1, further comprising a chuck mechanism for chucking at two positions in a direction perpendicular to the pattern surface. 5. The three positions are arranged in an equilateral triangle.
5. The mask according to claim 4, wherein when the mask structure is held by the chuck mechanism, one of the three is located in a direction extending from a center of the rectangular window in a direction parallel to a side of the rectangle. Holding device. 6. An exposure apparatus comprising: the mask holding device according to claim 1; and exposing a mask held by the mask holding device. 7. A step of preparing a mask structure having a mask substrate provided with a rectangular window on which a mask pattern is formed and a ring-shaped frame, and a wafer; and forming the frame from a direction in which a diagonal line of the rectangular window is extended. Correcting the mask pattern by applying a load to the mask, and transferring the mask pattern to the wafer by irradiating exposure energy while holding the mask structure and the wafer in a close proximity to each other. Device manufacturing method. 8. A mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame, wherein the frame has a rigidity in a diagonal direction of the rectangular window which is relatively large as compared with other directions. Preparing a mask structure and a wafer having a larger size, applying a load to the frame to correct the mask pattern, and holding the mask structure and the wafer in a positional relationship close to each other to expose the energy; Irradiating the wafer with a mask pattern to transfer the mask pattern onto the wafer. 9. The device manufacturing method according to claim 7, wherein said exposure energy is a radiation beam such as X-ray, vacuum ultraviolet ray or electron beam. 10. A mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame,
A mask structure, wherein the frame has a rectangular window whose diagonal rigidity is relatively large as compared with other directions. 11. The mask structure according to claim 10, wherein the mask structure is a mask structure for lithography using a radiation beam such as X-rays, vacuum ultraviolet rays, or electron beams.