JPH10242033A - 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 forming a rectangular window in which a mask pattern is formed on a mask substrate, and applying a load to the step of a frame with a stepped thin wall part in the periphery of a mask structure body. 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. A ring type retaining frame 13 for retaining and reinforcing the mask substrate 11 has a thin wall part whose upper surface is planed along the outer periphery of circumference, and constitutes a step structure having a step 16 when viewed from the side surface. Three protruding parts whose tops are spheres for retaining a mask are formed on a base plate. Three rotating arms corresponding to the protruding parts are installed. Two load units capable of rotating operation which apply loads, from two directions, to the step 16 of the retaining frame 13 of the mask are installed on the base plate.

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 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 to transfer the image at the same magnification, it is difficult to adjust the transfer magnification of the mask pattern transferred to the wafer. Kaisho 60-1824
In the X-ray exposure apparatus disclosed in Japanese Patent Publication No. 41, there is proposed a method of controlling a pattern magnification on a 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 comprising a mask substrate provided with a rectangular window on which a mask pattern is formed, and a thin portion having a step at its periphery. A chuck mechanism for holding a mask structure having a frame and a mechanism for applying a load to a step of the frame are provided.

Preferably, the mechanism for applying a load applies the load from a direction in which a diagonal line of a rectangular window of the mask substrate is extended.

[0008] Preferably, the mechanism for applying the load is 2
It has two pressing mechanisms for pressing the frame from two diagonal 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.

According to the device manufacturing method of the present invention, a mask structure and a wafer having a mask substrate provided with a rectangular substrate provided with a mask pattern and a frame formed with a thin portion having a step on its periphery are prepared. Correcting the mask pattern by applying a load to a step portion of the frame; and holding the mask structure and the wafer in a positional relationship close to each other and irradiating exposure energy to form a mask pattern on the wafer. A method for manufacturing a device, comprising a step of transferring.

Preferably, in the step of applying a load to the step portion of the frame to correct the mask pattern, a load is applied from a direction extending a diagonal line of a rectangular window of the mask substrate.

[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 frame supporting the mask substrate, and the frame has at least a frame extending in a direction extending a diagonal line of the rectangular window. A thin portion is provided in the periphery.

[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. As shown in FIG. 1, the shape of the support frame 13 is circular on the outer periphery, and a rectangular area corresponding to the rectangular window of the mask substrate is removed on the inner side to form a through hole 15. The shape of the through hole 15 is not limited to a rectangle, but may be a circle.

As shown in FIG. 1, the support frame 13 has a thin portion whose upper surface is cut off along the outer periphery of the circumference, and has a stepped portion 16 when viewed from the side. It has a step structure. The circumference of the upper stage of the support frame and the circumference of the mask substrate have substantially the same size.
The upper surface of the support frame 13, that is, the portion shown by the hatched portion 14 is a bonding surface with the mask substrate 11, and is bonded by a method such as adhesive bonding or anodic bonding. In FIG. 1, a mask substrate 1 is shown to explain the shape of the support frame.
Although shown as an exploded view in which the support frame 1 and the support frame 13 are disassembled, they are actually a structure in which they are joined 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 FIG.
This will be described with reference to FIG. 3 is a non-holding state of the mask structure, FIG. 4 is a cross-sectional view at a cross section indicated by an arrow in FIG. 3, FIG. 5 is a holding state of the mask structure, and FIG. Is shown.

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.
The block 601 includes two protrusions 61 that contact the step portion of the support frame of the mask structure at two points when viewed from above.
5, 616 are provided. On the base plate 612, three projections 6 each having a spherical end are provided for supporting the mask.
02, 603 and 604 are formed, and 3 corresponding to these are formed.
Two rotating arms 605, 606, 607 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 steps of the mask support frame from two directions. Each load unit includes a rod and the rod. It has a built-in detector (load cell) that detects the reaction force when a load is applied by the, and an actuator that rotates the load unit itself.

In the above structure, the mask structure 100 transferred by the transfer arm (not shown) is
The two support portions 615 and 616 are abutted, and XY horizontal positioning is performed. The mask structure 1 is formed at three points of the mask chuck protrusions 602, 603, and 604.
00 is supported, and three arms 605, 606,
By rotating the 607 and holding the frame of the mask from above and below at three places, all the positioning of the mask in the YYZ directions is completed. At this time, the protrusion of the arm 605 is formed by the V groove 10 formed on the upper surface of the frame of the mask structure 100.
5 so that there is no shift in the rotational direction.

Next, the load units 608 and 609 are rotated in the mask direction, and the ends of the rods 610 and 611 of each load unit are abutted against the step of the support frame of the mask structure as shown in FIGS. . At this time, the rods 610 and 611 that contact each other apply a load toward the center of the mask, and the directions in which the loads are applied are orthogonal to each other. As a result, loads are applied to the step portions of the support frame of the mask from four directions in which the diagonal lines of the rectangular windows of the mask are respectively 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.

FIG. 7 is a diagram 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. Support frame 1 with two-stage structure
4, the loads P1, P2 (P1 = P2 =
P). Furthermore, since two abutment fixing members 614 and 615 are arranged at respective opposing positions in which the vector directions of these additional loads are extended, each fixing member 61 is provided.
From 4 and 615, a reaction force (P) is applied to the support frame 13 toward the center of the mask. As a result, a force is applied to the step portion of the support frame 14 having the two-stage structure, that is, the outer circumference of the upper circle from four directions in which the two diagonal lines of the rectangular window are extended.

Since the position where the load is applied to the support frame is not at the center of the height of the side surface of the support frame as shown in FIG. 6, a moment is generated and the support frame and the mask substrate integrated therewith are generated. Is slightly warped, and the membrane stretched over the rectangular window is also slightly reduced. FIG. 6 exaggerates the state in which the frame is warped. By thus slightly reducing the overall membrane, the magnification of the mask pattern formed thereon can be changed.

FIG. 8 is a vector diagram showing a pattern displacement of the membrane of the rectangular window as a result of applying a load as shown in FIG. 7. As shown in FIG. 8, the mask pattern shows a substantially isotropic displacement. . The reason for this is that the mode in which the mask pattern on the membrane is reduced by the application of a force from the diagonal direction in the plane of the mask substrate and the mode in which the mask pattern on the membrane is reduced because the mask substrate is warped. This is because as a result of the synthesis, an isotropic pattern displacement (magnification reduction) is obtained as a whole. In addition,
If the additional loads P1 and P2 are made different, it is possible to reduce the magnification anisotropically.

Here, as a comparative example, a case where a load is applied not from the diagonal direction of the rectangular window but from the side direction using a flat support frame having no step is described. As shown in FIG. 9, 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 in the vector diagram of FIG. 10, the displacement at the diagonal position outside the rectangular pattern is small, and the horizontal and vertical positions are relatively largely displaced from the center, indicating a pincushion-shaped deformation. That is, the pattern is distorted compared to the isotropic uniform reduction as shown in FIG. 8, and the pattern distortion is increased.

In this embodiment, (1) a mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame for reinforcing the mask substrate, the frame being viewed from the side. When a load is applied to this step using a mask structure provided with a step,
(2) The best magnification correction with the least distortion is made possible by the synergistic effect of the combination of the two of applying a load to the step portion of the support frame from the direction in which the diagonal line of the rectangular window is extended. ) Or (2) enables magnification correction superior to those shown in FIGS. 9 and 10, so only one of them may be employed.

<Modification of Mask Structure> Next, a modification of the mask structure will be described with reference to FIGS. FIG.
In the inner periphery of the plate-like ring portion 23, the mask substrate 2
Four projections 24 are provided on four sides in the diagonal extension direction with respect to one square rectangular window 22. The projection 24 is joined to the plate-like ring 23 as a separate member, or is manufactured integrally with both. The plate-like ring portion 23 and the projection 24 together form a support frame. The protruding portion 24 is thicker than the plate-shaped ring portion, and a step portion 26 for applying a load to the support frame is formed at these joints. That is, the entire plate-like ring portion 23 is a thin portion of the support frame.

The upper surface of the projection 24 (shaded portion in FIG. 11) is a bonding surface with the mask substrate 21, and the outer circumference defined by the four projections 24 and the outer circumference of the mask substrate 21 are substantially equal. They match and are joined as shown in FIG.

As in the previous embodiment, this embodiment also has a mask substrate provided with a rectangular window on which a mask pattern is formed, and a ring-shaped frame for reinforcing the mask substrate. When viewed, a step is provided, and a load is applied to this step. Further, a load is applied to the step portion of the support frame from a direction in which a diagonal line of the rectangular window on which the mask pattern is formed is extended.

The mechanism for holding and applying a load while holding the mask structure is the same as that described with reference to FIGS.

Since it is essential to apply a load to the step portion of the support frame from the direction in which the diagonal line of the rectangular window is extended, as another modification, the support frame is provided at least in the direction in which the diagonal line of the rectangular window is extended. If a thin portion is provided around the frame, a load can be applied to the step portion. Therefore, instead of providing the thin portion on the entire periphery of the support frame as shown in FIG. 1, only the peripheral portions in four directions extending two diagonal lines of the frame may be thin portions.

<Exposure Apparatus> FIG. 13 is an overall configuration diagram 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 the exposure apparatus by the 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. 14 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. 15 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.

[0039]

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 an exploded view showing a mask structure according to a first embodiment.

FIG. 2 is a completed view of the mask structure of FIG. 1;

FIG. 3 is a top view showing a mask holding device (non-holding state).

FIG. 4 is a sectional view of FIG. 3;

FIG. 5 is a top view showing a mask holding device (holding state).

FIG. 6 is a sectional view of FIG. 5;

FIG. 7 is a diagram illustrating a relationship between a load applied to a mask structure and a rectangular window.

FIG. 8 is a diagram showing, as a vector, a change in magnification of a mask pattern when a load is applied.

FIG. 9 is a diagram showing a comparative example.

FIG. 10 is a diagram showing a comparative example of FIG. 8;

FIG. 11 is a diagram illustrating a mask structure according to another embodiment.

12 is a diagram showing a relationship between a load applied to the mask structure of FIG. 11 and a rectangular window.

FIG. 13 is an overall schematic view of an exposure apparatus.

FIG. 14 is a diagram showing a flow of a device manufacturing process.

FIG. 15 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 Through hole 16 Step part

Claims (11)

[Claims] 1. A chuck mechanism for holding a mask structure having a mask substrate having a rectangular window on which a mask pattern is formed, a frame having a thin portion having a step around the frame, and a chuck mechanism for holding the mask structure. A mask holding device having a mechanism for applying a load to a step. 2. The mask holding device according to claim 1, wherein the load applying mechanism applies the load from a direction in which a diagonal line of the rectangular window of the mask substrate is extended. 3. The mask holding device according to claim 2, wherein the load applying mechanism has two pressing mechanisms for pressing the frame from two diagonal 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 frame having a thin portion having a step around the mask substrate and a wafer; Correcting the mask pattern by applying a load to the step, 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. A device manufacturing method characterized by the above-mentioned. 8. The device according to claim 7, wherein in the step of applying a load to the step portion of the frame to correct the mask pattern, applying a load from a direction in which a diagonal line of a rectangular window of the mask substrate is extended. Production method. 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 frame supporting the mask substrate, wherein the frame has a thin portion provided at least around a frame extending in a direction extending a diagonal line of the rectangular window. A mask structure characterized in that: 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.