JPH10209018A - X-ray mask frame and maintenance of x-ray mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate cleansing of a cleaning mask of an X-ray mask with causing no deformation of the X-ray mask by so constituting that an action line of the mask maintenance force, by means of a mask maintenance member may not pass through the back etching part of the X-ray mask. SOLUTION: The back central part of a mask substrate 117 is subjected to back etching, a back etching part 126 is irradiated with an X-ray, and a pattern in almost the same form with an X-ray absorber metal pattern 119 is transcribed on an exposed substrate 121 as a resist pattern. At this time an X-ray mask 120 is detachably maintained in the inside of a frame main body 2 with two mask maintenance member for being made into a part where the line of action maintaining the X-ray mask 120 of this mask maintaining member 6 does not pass through the back etching part 126 of the X-ray mask 120. As a result, the X-ray mask 120 can be cleansed with no consideration of man-hour of connection and disconnection to an X-ray mask frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an X-ray mask frame for holding an X-ray mask for X-ray lithography and an X-ray mask frame.
The present invention relates to a method for holding a line mask.

[0002]

2. Description of the Related Art X-ray lithography has attracted attention as a technique for forming very fine patterns such as large-scale integrated circuits. FIG. 6 is a configuration diagram showing the principle of X-ray lithography. In X-ray lithography, an X-ray absorber metal pattern 119 or a part of X-rays is absorbed on an X-ray transparent thin film 118 formed on a surface of a mask substrate 117 made of silicon or the like by a CVD method (chemical vapor deposition) or the like. And an X-ray mask 1 in which a phase shifter pattern for changing the phase by a predetermined amount or both are arranged.
20 is used. Then, X-rays 122 are irradiated in a state where the substrate 121 to be exposed is arranged close to the X-ray mask 120,
The X-ray absorber metal pattern 1 on the substrate 121 to be exposed
An X-ray intensity distribution corresponding to the arrangement of the phase shifter pattern 19 and the phase shifter pattern is created. The X-ray photosensitive material 12 is previously placed on the substrate 121 to be exposed.
If 3 is applied, the X-ray photosensitive substance 123 is changed by the irradiation of the X-ray 122. The most typical example is a case where a resist is used as the X-ray photosensitive substance 123,
After irradiation with the X-rays 122, a pattern having substantially the same shape as the X-ray absorber metal pattern 119 is transferred as a resist pattern onto the substrate 121 to be exposed by performing a development process. As a special case, the exposed substrate 121 itself or the exposed substrate 1
In some cases, the surface material itself of 21 may be used as an X-ray photosensitive material.

Incidentally, the X-ray mask 120 is such that the mask substrate 117 is made of a fragile material such as silicon, and the X-ray transmitting thin film 118 is an extremely thin film of usually about 0.5 to 3 μm. If the surface of the X-ray mask 120 is easily broken, a foreign matter adheres to the surface of the X-ray mask 120, causing a transfer defect or transferring to the substrate 121 side to contaminate the substrate 121. For the purpose of not handling the X-ray mask 120 as much as possible, such as to avoid touching the X-ray mask 120 as much as possible, the X-ray mask 120 is made of glass, quartz, metal or the like and is attached to the X-ray mask frame 124 for use. Was.

In order to use X-ray lithography as a practical problem, the X-ray mask 120 and the substrate 121 to be exposed are set to be in close proximity to each other so as to form a minute gap.
It is necessary to repeat the operation of performing X-ray irradiation while sequentially changing the position of the substrate 121 to be exposed. In addition, it is necessary to inspect the defect of the X-ray mask 120, the dimension of the pattern on the mask, and the measurement of the positional accuracy of the pattern. X to do these
To attach the X-ray mask 120 to a device such as a line stepper, a defect inspection device, a pattern dimension measuring device, or a pattern position measuring device, or to transport the X-ray mask 120 in the device, a machine or a person must touch the X-ray mask 120. Absent. At that time, if the X-ray mask 120 is attached to the X-ray mask frame 124, the X-ray mask 120 does not need to be directly contacted. Therefore, the probability of damage to the X-ray mask 120 can be reduced, and contamination of the X-ray mask 120, and contamination and the like of the substrate 121 to be exposed due to transfer and adhesion of foreign matter can be prevented.

As described above, it is effective to use the X-ray mask 120 attached to the X-ray mask frame 124. However, in the conventional X-ray mask 120, when the X-ray mask 120 is attached to the X-ray mask frame 124 by bonding with the adhesive 125, there are some problems as described below.

[0006] The first problem is a problem that occurs with respect to the cleaning of the X-ray mask 120. That is, the X-ray mask 120
Will develop defects over time and over time. Defects may be generated in an atmosphere exposed to X-rays to be irradiated or in the substrate 121 to be exposed.
And a substance to which various substances in the X-ray photosensitive substance 123 react and are attached to dust floating in an exposure atmosphere.

[0007] Of these, defects generated in the membrane 118a, which is the X-ray transmitting portion of the X-ray transmitting thin film 118, act as an X-ray absorber, a semi-X-ray absorber or an X-ray phase shifter during X-ray irradiation. Detrimental transfer defects may result. Therefore, before actually using the X-ray mask 120, the presence or absence of such a harmful defect is inspected, and if a defect is present, the X-ray mask 120 is cleaned and used. This cleaning includes sulfuric acid, hydrogen peroxide, hydrochloric acid, nitric acid,
A strong acid such as ammonia, a strong alkali, an organic solvent or the like may be used alone or as a mixture, and may be sequentially washed with several kinds of chemicals. Therefore, if cleaning is performed with the X-ray mask 120 attached to the X-ray mask frame 124, the X-ray mask 1
Adhesive 125 used to attach X-ray mask frame 124 to 20 is often peeled off by the cleaning liquid. Further, the adhesive 125 may elute in the cleaning liquid and adhere to the X-ray mask 120, and conversely, the number of defects may increase. Further, since a human or a transport mechanism of an X-ray stepper is in contact with the X-ray mask frame 124, foreign substances adhering to the X-ray mask frame 124 may move and adhere to the X-ray mask 120 in some cases. It should be noted that a cleaning liquid that the adhesive 125 can withstand generally has a low cleaning ability, so that it is difficult to remove defects.

Further, as will be described later, the X-ray mask 120
In many cases, the bonding of the X-ray mask frame 124 to the X-ray mask frame 124 is performed at several points at most. Even if the bonding is performed around the entire periphery of the X-ray mask 120, the adhesive 125 is not completely uniformly applied. A minute gap is formed between the mask and the X-ray mask frame 124, and it is difficult to completely remove the cleaning liquid that has entered the gap. For this reason, in the liquid remaining between the X-ray mask 120 and the X-ray mask frame 124 during the drying after the cleaning, the foreign matter adhering as a mask defect and the foreign matter adhering to the X-ray mask frame 124 are left behind. . After drying, the gap between the X-ray mask 120 and the X-ray mask frame 124 changes, and the flatness of the X-ray mask 120 and the parallelism with respect to the mask frame 124 decrease. The X-ray mask 1 after cleaning
20 takes a long time to dry, or the X-ray mask 120 and X
There is also a problem that the substance remaining between the line mask frame 124 comes out later and becomes a factor of generating defects again.

On the other hand, to clean only the X-ray mask 120, it is necessary to remove the X-ray mask 120 from the X-ray mask frame 124. However, once the X-ray mask frame 1
It is very difficult to peel the fragile X-ray mask 120 firmly bonded to the adhesive 24 with the adhesive 125 without any damage. Further, if cleaning is performed with the adhesive remaining on the back surface of the X-ray mask 120, the X-ray mask 120 may be contaminated in reverse. Furthermore, after cleaning, it is necessary to adhere to the X-ray mask frame 124 again, which significantly increases the time and man-hour required for cleaning. If harmful defects remain in the inspection after cleaning, re-cleaning may be necessary. However, repeating the peeling and bonding of the X-ray mask 120 again causes a great loss of time, and the morale of the operator may be lost. Also has an effect.

The second problem is that the X-ray mask 1 caused by adhesion
Twenty distortion problems. That is, the bonding deforms the X-ray mask 120, which lowers the pattern position accuracy on the X-ray mask 120. The distortion varies depending on the amount, viscosity, adhesion location, adhesion area, and the like of the adhesive 125, but it is difficult to predict or control the distortion. Further, the flatness of the X-ray mask 120 may be reduced due to the adhesion. When the flatness of the X-ray mask 120 decreases, the unevenness of the close gap between the X-ray mask 120 and the substrate 121 to be exposed increases, so that the pattern line width and the planar shape and cross-sectional shape of the pattern in the exposure field and the wafer surface are reduced. Variation increases. When a very fine pattern is to be transferred by reducing the close gap to, for example, 15 μm or less, the resolution is affected by a slight difference in the close gap. A variation in resolution also occurs. In order to reduce the distortion of the X-ray mask 120 caused by such bonding as much as possible, the bonding between the X-ray mask 120 and the X-ray mask frame 124 is often performed at several points at most, and only one point is required from the viewpoint of distortion reduction. It is best to glue it. However, if they are bonded only at one point, vibration is likely to occur, and for example, the X-ray mask 12
If the mask surface is set horizontal when performing inspection 0 or pattern dimension measurement, it becomes like a cantilever.
A total load of 20 is applied to the bonding portion, and the adhesive is peeled off or tilted, and the parallelism with the substrate to be exposed is reduced. When the exposure is performed in the atmosphere, the X-ray extraction window and the X-ray mask 12 are used.
Helium is flowed between 0 and the X-ray extraction window and X-ray mask 12
To prevent the attenuation of X-rays between zero, helium becomes X
There is also a problem that a large amount of the helium is escaped from the gap between the line mask 120 and the X-ray mask frame 124, which causes an increase in the time required for helium replacement and a decrease in the helium replacement rate.

[0011]

As described above,
Conventionally, an X-ray mask is fixed to an X-ray mask frame with an adhesive, so that it is difficult to clean, or it requires a very large amount of labor and a long time to clean and make it usable again. There has been a problem that the line mask is deformed, resulting in a decrease in pattern position accuracy and flatness.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to use an adhesive without deforming an X-ray mask.
An X-ray mask frame and an X-ray mask that can easily clean the X-ray mask and maintain good pattern position accuracy and flatness.
An object of the present invention is to provide a method for holding a line mask.

[0013]

According to a first aspect of the present invention, there is provided an X-ray mask frame provided on a frame main body, wherein a side surface of the X-ray mask is perpendicular to a thickness direction of the X-ray mask. A mask holding member for holding the mask from above, and the line of action of the mask holding force by the mask holding member does not pass through the back-etched portion of the X-ray mask. Further, in the X-ray mask frame according to the second invention, in the first invention, the point of action of the force of the mask holding member on the X-ray mask is outside the back-etched portion and passes through the center of the back-etched portion. It is characterized by being substantially symmetrical with respect to the position. Further, X according to the third invention
In the first or second invention, at least two mask holding members are provided so as to face each other across the X-ray mask. The X-ray mask frame according to a fourth aspect of the present invention, in the first, second, or third aspect, wherein the mask holding member is provided so as to be movable in a direction in which the mask holding member approaches and separates from the X-ray mask. The other mask holding member facing the mask holding member across the line mask is a fixed holding portion or a fixed holding member provided on the frame body. An X-ray mask frame according to a fifth invention is characterized in that, in the first, second, third or fourth invention, the mask holding member is held by a spring and urged in the X-ray mask direction. And An X-ray mask frame according to a sixth aspect is the mechanism according to the first, second, third, fourth, or fifth aspect, wherein the mask holding member is locked at a standby position retracted from the X-ray mask. It is characterized by having. An X-ray mask frame according to a seventh aspect of the present invention is the X-ray mask frame according to the sixth aspect, wherein a recess is provided in the frame body, a mask holding member is provided in the recess, a spring for holding the mask holding member, and a mask holding member. And a mechanism for locking the mechanism at a standby position. An X-ray mask frame according to an eighth aspect of the present invention provides the X-ray mask frame according to any one of the first to seventh aspects, wherein the engagement portion engages with a step portion provided on a side surface of the X-ray mask. Is provided on the mask holding member.

According to a ninth aspect of the present invention, there is provided a method for holding an X-ray mask, comprising: mounting an X-ray mask on a surface of an X-ray mask frame;
It is characterized in that a position where the line of action of the force holding the line mask does not pass through the back-etched portion of the X-ray mask is held. Further, the method of holding an X-ray mask according to the tenth aspect of the present invention is a method of holding an X-ray mask suitable for reducing or correcting an amount of a pattern on the X-ray mask transferred by runout in a direction in which an exposure field spreads. Distortion is caused by pressing the position where the line of action of the force holding the X-ray mask does not pass through the back-etched portion of the X-ray mask, and the amount of pattern shift due to run-out during exposure is reduced or corrected. It is characterized by holding an X-ray mask.

The X-ray mask frame has a mask holding member for holding the X-ray mask. When the X-ray mask is removed from the X-ray mask frame, only the X-ray mask can be cleaned, and after the cleaning is completed, the X-ray mask can be easily attached to the X-ray mask frame again. The mask holding member has a line of action of the force holding the X-ray mask on the side surface of the X-ray mask.
Since a portion of the line mask that does not pass through the back-etched portion is held, the exposure field of the X-ray mask is deformed while maintaining a substantially square shape in the case of a square shape. If the amount of deformation is substantially the same in the reverse direction as the amount by which the exposure field spreads due to the run-out during pattern transfer, the run-out can be offset, and the pattern on the X-ray mask manufactured with the correct exposure field dimensions can be corrected. Can be transferred onto the substrate to be exposed with an exposure field size of

When the mask holding member is pressed against the X-ray mask by a spring, a predetermined mask holding force determined by the strength of the spring is applied to a predetermined position of the X-ray mask. X in attached state
The amount of distortion of the line mask is constant and reproducible, and the amount of distortion can be controlled by changing the strength of the spring that holds the X-ray mask. Further, by appropriately selecting the strength of the spring, the distortion of the X-ray mask can be set to be equal to or less than the allowable value. Also, since the X-ray mask only applies a holding force in the surface direction of the X-ray mask, in other words, in the direction perpendicular to the thickness direction, even if the X-ray mask is attached to the X-ray mask frame,
No deterioration in flatness occurs.

The locking portion of the mask holding member engages with a step provided on the side surface of the X-ray mask to restrict the movement of the X-ray mask in the thickness direction and prevent the X-ray mask from falling off the mask holding member. To prevent.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 shows the X according to the present invention.
FIG. 2 is an exploded perspective view showing an embodiment of the X-ray mask frame, and shows a state where the X-ray mask is attached to the X-ray mask frame. As shown in FIG. 6, the X-ray mask 120 has an X-ray transparent thin film 118 formed on a surface of a mask substrate 117 made of silicon or the like by a CVD method or the like.
An X-ray absorber metal pattern 119 and / or a phase shifter pattern that partially absorbs X-rays and changes the phase thereof by a predetermined amount are arranged thereon. The back surface of the mask substrate 117 is back-etched, and the back-etched portion 126 (see FIG. 6) is irradiated with the X-rays 122 so that a pattern having substantially the same shape as the X-ray absorber metal pattern 119 is covered. It is transferred as a resist pattern on the exposure substrate 121. In this embodiment, the back etching portion 126 is formed in a rectangular shape, and a portion covering the back etching portion 126 forms a membrane 118a that is an X-ray transmitting portion.

The X-ray mask frame 1 on which the X-ray mask 120 is mounted has a frame body 2 made of a square or rectangular plate having a required thickness, and a surface of the frame body 2, that is, an X-ray mask. An upper and a lower cover (5, 5) are provided to cover the surface facing the substrate to be exposed 121 with the X-ray mask (120) exposed, and the X-ray mask (120) is detachably mounted inside the frame body (2). Two mask holding members 6 and 6 having the same shape to be held are assembled so as to oppose each other in the vertical direction with the X-ray mask 120 interposed therebetween.

The frame body 2 is made of metal or the like.
On the front surface side, two cover concave portions 7 into which the respective covers 5 are detachably fitted are formed, and concave portions 8 for accommodating the mask holding members 6 are formed on the bottom surfaces of the respective concave portions 7. . The shape and depth of the recesses 7 and 8 are arbitrary. The surface height relationship between the central portion where the X-ray mask 120 is installed on the surface of the frame main body 2 and its peripheral portion may be arbitrary. In order to finish the central portion where the X-ray mask 120 is installed with high flatness, it is better that the portion is flush with the peripheral portion or protruded from the peripheral portion. However, in order to reduce the total thickness of the X-ray mask 120 and the frame main body 2 and to facilitate positioning when the X-ray mask 120 is mounted, the portion where the X-ray mask 120 is installed is located closer to the periphery. A low depression may be used, and the X-ray mask 120 may be fitted therein.

The mask holding member 6 is formed by bending a metal plate or the like. The base is fixed to the center of a leaf spring 9 by a plurality of screws 11 via a spring retainer 10. Left and right 2 holding the side of 120
One holding part 13 is provided integrally. In the side surface portion of the X-ray mask 120 held by the holding unit 13, the line of action of the force of holding the X-ray mask 120 (mask holding force) of the mask holding member 6 does not pass through the back etching unit 126 of the X-ray mask 120. Location. That is, as shown in FIG.
The line of action or extension of the mask holding force F with respect to 0 is outside the back etching portion 126 of the X-ray mask 120 and passes through the center O of the back etching portion 126.
The position is substantially equidistant on both sides of the line 5, in other words, the position is substantially symmetric with respect to the line 15.

The holding section 13 is bent toward the X-ray mask 120 and protrudes toward the surface of the frame body 2. The protrusion amount of the holding portion 13 is set smaller than the thickness of the X-ray mask 120. Since the X-ray mask 120 is made of a fragile material such as silicon, the portion of the mask holding member 6 protruding toward the surface of the frame body 2 and the X-
It is more preferable that the cushioning member 16 such as a sheet made of rubber, sponge, polymer material, or the like be attached to the contact surface that comes into contact with the line mask 120. Due to handling of the X-ray mask 120, X-ray stepper, X-ray mask defect inspection device, X-ray mask pattern dimension measuring device, X-ray mask pattern position measuring device, etc. Care is taken so that the line mask 120 does not come off or deviate from the frame body 2.

The leaf spring 9 is disposed horizontally in the recess 8, and both ends thereof are fixed to the wall surface of the recess 8 by a plurality of screws 18 via a spring retainer 17, whereby the mask holding member is provided. 6 is urged in the X-ray mask 120 direction. The mask holding member 6 attached to such a leaf spring 9 is movable only in the vertical direction perpendicular to the plane of the leaf spring 9, and the cover 5 and the concave portion are 8 regulations.

However, if the mask holding member 6 is reliably guided by holding the mask holding member 6 with a parallel leaf spring, for example,
It is not always necessary to regulate the movement in the front-back, left-right direction by the cover 5 and the recess 8. Conversely, if the mask holding member 6 is guided by the cover 5 and the concave portion 8,
The leaf spring 9 simply urges the mask holding member 6 in the X-ray mask 120 direction. In that case, a coil spring or the like may be used instead of the leaf spring 9. In short, the type and number of springs for applying the mask holding force F for holding the X-ray mask 120 and for guiding the mask holding member 6 are arbitrary. The method of attaching the cover 5 to the frame main body 2 is not limited to the fitting, and may be attached by bonding, screwing, or the like. It goes without saying that the materials of the components constituting the X-ray mask frame 1 may be arbitrary. Further, the cover 5 may be attached to the frame body 2 so as to be openable and closable.

In this embodiment, as shown in FIG. 1, the mask holding member 6 and the leaf spring 9 are provided so as to oppose each other vertically with the X-ray mask 120 interposed therebetween. May be. Also, it is not always necessary to do so. For example, one mask holding member 6 may be fixed to the frame main body 2, only the other mask holding member 6 may be attached to the leaf spring 9, and the other mask holding member may be pressed against the X-ray mask 120. In this case, it is not always necessary to use the same mask holding member 6 on the fixed side as the mask holding member 6 on the movable side. What is necessary is just to provide a holding member.

FIGS. 2A and 2B are diagrams showing the relationship between the location where the X-ray mask is held and the manner in which the membrane is distorted. FIG. 2A shows the line of action of the mask holding force F holding the X-ray mask 120 or its extension. When two points at the center of the line mask 120 passing through the back etching section 126 are held, (b) shows the back etching section 126 by the X-ray mask frame 1 shown in FIG.
This is a case in which four points are held on the outer side and on both sides of the line 15 passing through the center O of the back etching portion 126 at substantially equal distances. (A) In the holding state shown in the figure, since the mask holding force F passes through the center of the back etching portion 126, the membrane 11 of the X-ray transmitting thin film 118
8a is deformed into a pincushion shape as shown by a broken line 30 when exaggerated. If the membrane 118a is deformed into such a pincushion shape, the deformation is not uniform, so that it becomes difficult to use the run-out correction described later.

On the other hand, in FIG. 2B, since the X-ray mask 120 is held outside the back-etched portion 126, the mask holding force F is lower than that of the X-ray mask 1.
20, the membrane 11 of the X-ray transparent thin film 118
8a is compressed and deformed in the direction of action of the mask holding force F while maintaining a substantially rectangular shape as shown by a broken line 31 when exaggerated. In this case, the deformation of the X-ray mask 120 due to the holding can be offset with the runout at the time of transfer, and the transfer position error due to the runout can be effectively corrected.

When the pattern on the X-ray mask 120 is transferred onto the substrate to be exposed, since the size of the light emitting point of the X-ray source is generally smaller than the size of the exposure field, the fact that the X-ray 122 diverges naturally is used. The X-rays 122 are irradiated on the entire exposure field by scanning the X-rays in one direction or in two orthogonal directions, for example, by expanding the X-ray flux with a reflecting mirror or the like. Therefore, the X-ray mask 120 is irradiated with the X-rays 122 spreading outward, and the pattern field on the X-ray mask 120 is spread and transferred onto the substrate to be exposed according to the irradiation angle of the X-rays 120. This is called the "run-out phenomenon."

When X-ray lithography is applied to pattern formation of a large-scale integrated circuit or an optical element, it is necessary to repeat pattern formation on a substrate to be exposed in order to form an element structure. In addition to the formation, a new layer pattern must be transferred so as to be accurately superimposed on a pattern already formed on the substrate to be exposed. When the amount of run-out due to the above-mentioned run-out phenomenon is large, all the layers may be formed by the same X-ray lithography. However, a layer having only a large pattern may be formed using low-cost optical lithography, or a fine hole pattern may be formed. If other lithography means, such as forming using electron beam lithography, coexist, it will not be possible to transfer a new pattern accurately over the existing pattern with the required precision. This is because, when lithography means other than the X-ray lithography technique is used, no run-out occurs and the size of the exposure field differs.

The use of the X-ray mask frame 1 of the present invention can reduce or correct the amount of the pattern field spread by the run-out phenomenon and transferred to the substrate to be exposed. That is, as described above, the X-ray mask 1
Since the mask 20 is held on the X-ray mask frame 1 by pressing it in the direction in which the mask contracts inward, the distortion of the X-ray mask 120 occurs in the direction opposite to the above-described run-out phenomenon. Therefore, the run-out can be reduced by using the distortion of the X-ray mask 120 due to the holding, and if the amount of the distortion due to the holding is made equal to the amount of the run-out in the opposite direction, it is possible to completely correct the run-out.

Referring to FIG. 1, in order to mount the X-ray mask 120 on the X-ray mask frame 1 of the present invention, the X-ray mask 1 is retracted with the mask holding member 6 retracted against the leaf spring 9.
20 is set on the frame body 2. In order to facilitate this operation, it is preferable that the mask holding member 6 can be locked at the retracted position.

FIG. 3 is a front view showing another embodiment of the present invention provided with a mechanism for locking the mask holding member at a standby position retracted from the X-ray mask. The upper half of FIG. 3 is shown in FIG. The state where the cover 5 is removed is shown, and the lower half shows the state where the cover 5 is attached. In the figure, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Although not shown in FIG. 1, at the center of the surface of the frame body 2 where the X-ray mask is installed,
A rectangular opening 40 that allows irradiation of the X-ray mask with exposure X-rays is formed. In the figure, the opening is substantially rectangular, but may be an opening of any shape such as a circle or a rectangle.

The cover 5 that covers the surface of the frame body 2 has long holes 51 and 52 that are long in the vertical and horizontal directions, respectively.
A protrusion 53 protruding from the mask holding member 6 is slidably fitted in a long hole 51 which is formed one by one and is long in the vertical direction. On the other hand, a stopper 54 that locks the mask holding member 6 at a position where the mask holding member 6 is retracted from the X-ray mask, that is, a standby position is slidably fitted into the elongated hole 52 that is long in the lateral direction.

On the bottom surface of each recess 7 formed on the surface of the frame body 2, in addition to the recess 8 for accommodating the mask holding member 6, two recesses 55, 55 are opposed to each other with the mask holding member 6 interposed therebetween. , And are formed so as to communicate with the recesses 8, and the stoppers 54,
A compression coil spring 57 for pressing the stopper 54 against the mask holding member 6 is housed. The stopper 54 is normally pressed against the outer surface of the mask holding member 6, and when the mask holding member 6 is retracted from the X-ray mask, the compression coil spring 5
The mechanism 7 is engaged with the recess 58 provided on the outer surface of the mask holding member 6 by the force of 7, thereby constituting a mechanism for locking the mask holding member 6 at a standby position retracted from the X-ray mask. To release the locked state of the mask holding member 6, the stopper 54 may be moved along the elongated hole 52 against the compression coil spring 57 to release the engagement state with the concave portion 58. The shape of the portion of the stopper 54 that engages with the recess 58 is an arc surface or a spherical surface having an appropriate radius or a smooth shape with a chamfer.
If the mask holding member 6 is engaged with the recess 58 of the mask holding member 6 by pushing the mask holding member 6 in the direction for holding the X-ray mask without moving the stopper 54, Can be disengaged,
It is possible to quickly return to the holding position of the X-ray mask.

FIG. 3 shows an example in which the concave portion 58 is provided on the outer surface of the mask holding member 6, but the position where the concave portion 58 is provided is arbitrary. For example, the inner surface of the mask holding member 6 may be used. In that case, the stopper 54 and the compression coil spring 57 may be provided so as to correspond to the recess 58. Also,
It is also possible to form a recess for accommodating the stopper 54 and the compression coil spring 57 on the bottom surface of the recess 8 provided in the frame main body 2 and provide the recess 58 on the back side surface of the mask holding member.
The shapes of the concave portions 55, 58 and the like are rectangular as shown in the figure, V-grooves,
The shape may be a U-shaped groove or the like, or a hole or a slit instead of a concave portion. The type and shape of the stopper 54 and the spring 57 are also arbitrary. Also, the spring 57 is
4 may be used. For example, a part of the leaf spring attached to the frame body 2 or the cover 5 may be hooked on the recess 58 to hold the mask holding member 6 at a predetermined position.

On the contrary, the frame body 2 and the cover 5
May be provided with a concave portion, a hole or a slit, and a stopper for engaging with the concave portion, the hole or the slit may be provided on the mask holding member 6 side.

FIG. 4 is a front view of a still further embodiment of the present invention with a cover removed. In the embodiment shown in FIGS. 1 and 3, two mask holding members 6 are provided.
Has shown an example in which the X-ray mask 120 is pressed from above and below and held at four points. However, in the present embodiment, the X-ray mask is
That is, it is pressed from the vertical and horizontal directions and held at eight points.

A circular opening 40 is provided at the center of the frame body 2.
Is formed on the front surface side, and one concave portion 70 that surrounds the entire periphery of the opening 40 and accommodates all four mask holding members 6 is formed. The shape of the opening 40 is not limited to a circle but may be an arbitrary shape such as a square or a rectangle, as in the embodiment shown in FIG. An annular portion 72 provided between the opening 40 and the concave portion 70 on the surface of the frame body 2 protrudes from the concave portion 70, and the surface forms an installation surface of the X-ray mask. The height relationship between the surface of the frame body 2 and the installation surface on which the X-ray mask is installed may be arbitrary. The four corners of the frame main body 2 support the leaf spring 9 with a spring retainer 17 and the like, and guide the mask holding member 6. In addition, a total of eight projections 74 projecting from each inner wall of the recess 70 are used as fixing portions for screwing a cover (not shown) to the frame body 2. The shape of the projection 74 is arbitrary, and is not necessary depending on how the cover is attached to the frame body 2. The number of covers is arbitrary, and may be one.

Each mask holding member 6 is integrally provided with two holding portions 13 and is fixed to the center of a leaf spring 9 having both ends fixed in the same manner as in the above-described embodiment. Hold. As shown in FIG. 2B, the holding portion 13 of each mask holding member 6 has a line of action of the mask holding force F for holding the X-ray mask or an extension thereof outside the back etching portion of the X-ray mask. In addition, it is located at a position substantially equidistant on both sides of a line passing through the center of the back etching portion.

Although not shown, it is more convenient to provide a stopper for locking each of the mask holding members 6 at the retracted standby position as in the embodiment shown in FIG. Also,
One of the four mask holding members 6 in the horizontal and vertical directions is fixed to the leaf spring 9 and the remaining mask holding members are held and fixed or fixedly held on the frame body 2 or the cover. It may be.

On the fixed side, it is not always necessary to use the same one as the mask holding member 6, and a fixed holding portion or a fixed member of any shape for supporting the substrate to be exposed may be provided. In this case, the X-ray mask may be attached by applying the X-ray mask to the fixed side and pressing the mask holding member on the opposite side against the X-ray mask.

FIG. 5 is a sectional view showing still another embodiment of the present invention. In this embodiment, a step portion 80 is provided on the peripheral surface of the X-ray mask 120 substantially all around or partially only on a part thereof.
The mask holding member 6 is provided with an engaging portion 81 that regulates the movement of the mask holding member 20 in the thickness direction. This engaging part 81 also serves as a holding part.

Since the side surface of the X-ray mask 120, that is, the surface forming the periphery, is often a surface having no step, such as a cylindrical surface or a flat surface, it is similar to the embodiment shown in FIGS. 1, 3, and 4. The X-ray mask 120 is supported only by the frictional force between the end surface of the mask holding member 6 and the side surface of the X-ray mask 120 in the thickness direction. Therefore, when any force in the thickness direction is applied to the X-ray mask 120, there is a concern that the X-ray mask 120 may come off the X-ray mask frame 1. However, as shown in FIG. 5, if the step portion 80 is provided on the side surface of the X-ray mask 120 and the engaging portion 81 that engages with the step portion 80 is provided on the mask holding member 6, the thickness of the X-ray mask 120 can be reduced. X-ray mask 1 even if force in the direction is applied
20 does not come off the X-ray mask frame 1. Other configurations are the same as those of the embodiment shown in FIG. 1, FIG. 3, or FIG.

In the embodiment shown in FIGS. 1, 3, 4 and 5, the shape of the frame main body 2 is square,
The shape is not limited to this, and may be any shape such as a circle or a rectangle.
The chamfer 83 is provided as shown in FIG.
A cut portion 84, a notch, or the like for easily identifying the direction of 20 may be provided. Also in FIG.
Is arbitrary.

The external shape and size of the X-ray mask 120 to which the present invention is applied are also arbitrary. 1, 3,
The present invention can be applied not only to a circular X-ray mask assumed in the embodiment of FIG. 4 or an X-ray mask provided with an orientation flat but also to a rectangular X-ray mask.

[0046]

As described above, according to the X-ray mask frame of the present invention, the mask holding member provided on the frame body and holding the side surface of the X-ray mask from a direction perpendicular to the thickness of the X-ray mask is provided. Since the line of action of the mask holding force by the mask holding member is prevented from passing through the back-etched portion of the X-ray mask, the X-ray mask can be easily attached to and detached from the X-ray mask frame and adhered with an adhesive. No need. Therefore, the X-ray mask can be cleaned without considering the number of steps for attaching and detaching the X-ray mask frame. In addition, since the external shape of the X-ray mask frame attached to the X-ray mask frame can be made almost the same as the case where the X-ray mask is bonded to the X-ray mask frame, not only X-ray exposure but also X-ray mask defect inspection and
The dimension measurement and position measurement of the pattern on the line mask can be performed in the same manner as in the case of the X-ray mask adhered to the X-ray mask frame using a conventional apparatus. Further, among the various devices described above, X
When the X-ray mask is mounted on a device that holds the X-ray mask horizontally, vibration of the X-ray mask or. The inclination angle of the X-ray mask generated at the time of mounting can be made considerably smaller than in the case of one-point bonding.

In the present invention, since the mask holding member is held by the spring and urged in the X-ray mask direction, the X-ray mask can be held with a substantially constant mask holding force.

Further, since the present invention is provided with a mechanism for locking the mask holding member at the standby position retracted from the X-ray mask, the work of attaching and detaching the X-ray mask is easy.

According to the present invention, a recess is provided in the frame body, and a mask holding member, a spring for holding the mask holding member, and a mechanism for locking the mask holding member at the standby position are accommodated in the recess. Therefore, the frame body can be made thin.

Further, in the present invention, since the mask holding member is provided with the engaging portion for engaging with the step provided on the side surface of the X-ray mask, it is possible to restrict the movement of the X-ray mask in the thickness direction. it can.

Further, in the present invention, when storing the mask, the X-ray mask can be stored in a conventional storage case while holding the X-ray mask with the X-ray mask frame. It can also be stored. If the X-ray mask is stored while being attached to the X-ray mask frame, it can be used immediately, but an extra storage space is required for the X-ray mask frame. Also, X-ray mask frames are required for the number of X-ray masks.
If the X-ray mask frame of the present invention is used, an X-ray mask which is to be used for the time being is stored while being attached to the X-ray mask frame, and an X-ray mask which is not to be used for the time being is stored only with the X-ray mask. The storage method can be arbitrarily devised.
Further, since the attachment and detachment of the X-ray mask are easy, it is possible to store the X-ray mask using only the X-ray mask. Therefore, effects such as cost reduction by saving the X-ray mask frame and saving of the X-ray mask storage space can be expected.

Further, according to the present invention, the X-ray extraction window and the X-ray
When used for an exposure apparatus in the atmosphere where the space between the X-ray mask and the back surface of the X-ray mask is replaced with helium, leakage of helium from between the X-ray mask and the X-ray mask frame can be reduced. When the X-ray mask is bonded to the X-ray mask frame at several points or less as in the related art, helium for replacement leaks from the bonding gap between the X-ray mask and the X-ray mask frame. However, in the present invention, the X-ray mask is placed on the X-ray mask frame, the side surface of the X-ray mask is held by the mask holding member, and an intentional gap is formed between the X-ray mask and the X-ray mask frame. Since it is not provided, a gap that becomes a helium leakage flow path becomes narrower than the conventional case. Therefore, the helium consumption can be reduced and the time required for helium replacement can be shortened.

Further, according to the X-ray mask frame and the method of holding the X-ray mask according to the present invention, it is possible to reduce or correct the amount of the pattern field spread by the run-out phenomenon and transferred onto the substrate to be exposed. That is,
Since the X-ray mask is pressed in the direction in which the mask shrinks inward and held on the X-ray mask frame, distortion of the X-ray mask occurs in the direction opposite to the run-out phenomenon. Therefore,
The run-out can be reduced by utilizing the distortion of the X-ray mask caused by the holding, and the distortion can be completely corrected if the amount of the distortion caused by the holding is equal to the run-out amount in the opposite direction.

When using synchrotron radiation X-rays, X-rays are generally extracted in a substantially horizontal direction, and the beam shape is long in the horizontal direction and short in the vertical direction. Therefore, using a mirror or the like to expand the X-ray flux in the vertical direction,
The required exposure field size is secured by scanning the X-ray flux in the vertical direction. In such a case, the runout is large only in the vertical direction. Therefore, in the X-ray mask frame of the present invention, as shown in FIG. 1, if the X-ray mask is held in only one direction and the holding direction is the vertical direction, the holding of the mask substrate in the vertical direction The run-out is corrected by the minute distortion, and the pattern on the X-ray mask can be transferred onto the substrate to be exposed with the original exposure field size.

On the other hand, in the case of using a plasma X-ray source or an X-ray source excited by an exposure beam, generally, the beam shape and the emission angle distribution are substantially symmetric with respect to the emission axis. Therefore, the run-out also occurs in the exposure field in the same amount in the vertical and horizontal directions. As described above, when the run-out occurs substantially axisymmetrically in the exposure field, the X-ray mask of the present invention holds the X-ray mask with two orthogonal forces as shown in FIG. If the small distortion caused by the holding is made substantially the same in two orthogonal directions, the run-out can be accurately canceled, and the pattern on the X-ray mask can be transferred onto the substrate to be exposed with the original exposure field size.

As described above, if the pattern on the X-ray mask can be transferred onto the substrate to be exposed with the original exposure field size, the pattern formed by photolithography or electron beam drawing can be used over the entire area of the exposure field. Superposition can be performed with high accuracy.

In the above description, the case where a pattern formed by X-ray lithography is superimposed on a layer formed by other lithography means has been described.
Even when a pattern formed by other lithography means is superimposed on a layer previously formed by X-ray lithography, if the run-out is reduced or corrected using the X-ray mask frame of the present invention, the overlay accuracy can be improved. It goes without saying that it can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of an X-ray mask frame according to the present invention with an X-ray mask attached.

FIGS. 2A and 2B are diagrams showing the relationship between the location where the X-ray mask is held and the manner in which the membrane is distorted. FIG. 2A shows the line of action of the mask holding force holding the X-ray mask or an extension of the X-ray mask back etching. If you hold two points at the center passing through the part,
(B) shows a case in which four points are held by the X-ray mask frame shown in FIG. 1 at positions equidistant to the outside of the back-etched portion and on both sides of a line passing through the center of the back-etched portion. .

FIG. 3 is a front view showing another embodiment of the present invention.

FIG. 4 is a front view of a still further embodiment of the present invention with a cover removed.

FIG. 5 is a cross-sectional view showing still another embodiment of the present invention.

FIG. 6 is a configuration diagram showing the principle of X-ray lithography.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... X-ray mask frame, 2 ... frame main body, 5 ... cover, 6 ... mask holding member, 7, 8 ... recessed part, 9 ... leaf spring,
13: holding portion, 54: stopper, 57: compression coil spring, 58: concave portion, 80: step portion, 81: engaging portion, 118
... X-ray transmitting thin film, 119 ... X-ray absorber metal, 120 ... mask substrate, 123 ... substrate to be exposed, 125 ... adhesive, F ...
Mask holding power.

Claims (10)

[Claims] A mask holding member provided on the frame main body for holding a side surface of the X-ray mask from a direction orthogonal to a thickness of the X-ray mask, and a line of action of a mask holding force by the mask holding member is an X-ray mask. An X-ray mask frame, which does not pass through the back-etched portion. 2. The X-ray mask frame according to claim 1, wherein the point of application of the mask holding force to the X-ray mask is located outside the back-etched portion and substantially symmetrical with respect to a line passing through the center of the back-etched portion. X characterized by being
Line mask frame. 3. The X-ray mask frame according to claim 1, wherein at least two mask holding members are provided to face each other across the X-ray mask. 4. The X-ray mask frame according to claim 1, wherein a mask holding member is movably provided in a direction approaching and separating from the X-ray mask, and the mask is sandwiched between the X-ray masks. An X-ray mask frame, wherein the other mask holding member facing the holding member is a fixed holding portion or a fixed holding member provided on the frame body. 5. The X-ray mask frame according to claim 1, wherein the mask holding member is held by a spring and urged in the X-ray mask direction. 6. X according to claim 1, 2, 3, 4 or 5.
An X-ray mask frame, comprising: a mechanism for locking a mask holding member at a standby position retracted from an X-ray mask. 7. The X-ray mask frame according to claim 6, wherein a recess is provided in the frame body, and the mask holding member, a spring for holding the mask holding member, and the mask holding member are in a standby position in the recess. An X-ray mask frame containing a stopping mechanism. 8. The X-ray mask frame according to claim 1, wherein the mask holding member has an engaging portion that engages with a step provided on a side surface of the X-ray mask. An X-ray mask frame. 9. An X-ray mask is mounted on a surface of an X-ray mask frame, and a line of action of a force for holding the X-ray mask on a side surface of the X-ray mask by a mask holding member is applied to a back etching portion of the X-ray mask. A method for holding an X-ray mask, characterized by holding a position that does not pass through. 10. An X-ray mask distortion suitable for reducing or correcting an amount by which a pattern on an X-ray mask is shifted in a direction in which an exposure field spreads due to a runout is reduced or corrected.
The X-ray mask is generated in a state in which the line of action of the force holding the X-ray mask is pressed at a position that does not pass through the back-etched portion of the X-ray mask, and the pattern shift amount due to run-out during exposure is reduced or corrected. A method for holding an X-ray mask, comprising: