JPH0570927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray transfer apparatus used in a phosphorography process, particularly in a transfer process, for manufacturing semiconductor devices with highly integrated circuits.

As the degree of integration of circuits increases, the width of the lines constituting the circuit pattern is required to be on the order of microns or submicrons, and to achieve this, the irradiation energy required to transfer the circuit pattern is required. Also, ultraviolet rays, far ultraviolet rays, and soft X-rays with increasingly shorter wavelengths are being used.

Efforts have been made to commercialize lithography equipment that uses soft X-rays for more than 10 years, but to this day, a practical X-ray transfer equipment for semiconductor device production has not yet been completed. . This is thought to be due to insufficient balance or optimization of printing resolution, alignment accuracy, throughput, device reliability, operability, device price, etc., which are requirements for practical use.

However, when considering the requirements for realizing an X-ray transfer device in more detail, one of the problems is that soft X-rays are much more difficult to handle than visible light or ultraviolet light. As is well known, soft X-rays must be generated in a vacuum container, so the soft Derive the line. Berylium is soft
It was chosen because it has an extremely low absorption ratio of radiation, but it was chosen so that it could withstand the pressure difference between the high vacuum inside the container and the atmospheric pressure where the mask and wafer were placed.
A thickness of approximately 50 microns is required. Beryllium foil has a soft X-ray absorption rate of 50 when it reaches this thickness.
%, which is disadvantageous.

Furthermore, in addition to this, the following difficulties were noted by the inventors of the present invention. FIG. 24 shows the relationship between the intensity (vertical axis) and energy of soft X-rays generated by irradiating a target with an accelerated electron beam. The smooth downward-sloping curve is a continuous line, and the peak that stands out in the middle is a characteristic line. The characteristic line is related to the material of the target.

Here, the side smaller than about 4 KeV is used for irradiating the photosensitive material, but since the area to the left of the broken line is absorbed by beryllium, the energy actually used for irradiation is sandwiched between the position of about 4 KeV and the broken line. It is just a limited area.

That is, a large energy loss is involved when extracting soft X-rays from the vacuum section.

Another problem arises from irradiating the mask with divergent soft x-rays. If the mask and wafer are kept in close proximity and are exposed to divergent soft X-rays, and the wafer is tilted,
The dimensions of the mask image change in areas where the mask and wafer have approached and areas where they have moved away from each other. Therefore, although it is necessary to strictly maintain the parallelism between the mask and the wafer, it is extremely difficult to achieve this mechanically. In addition, when irradiating with a divergent beam, the dimensions of the mask image differ between the center and the periphery, so each transfer requires not only alignment of the mask and wafer, but also alignment between the center of the mask and the axis of the X-ray source. It needs to fit your personality.

Yet another problem is that when a wafer after pattern transfer is subjected to chemical processing such as etching, the wafer expands and contracts. In particular, the diameter of wafers has recently increased significantly, and there is a demand for transfer to 6-inch or 8-inch diameter wafers, and the expansion and contraction of wafers cannot be ignored. Therefore, it is necessary to minimize the influence of expansion and contraction of the wafer on the pattern image.

Therefore, it is a primary object of the present invention to provide an X-ray transfer device in which energy from an X-ray source can be effectively utilized for irradiating a mask.

On the other hand, if a substance is left in a vacuum, the gas occluded in the surface layer of the substance will be released, significantly impairing the degree of vacuum, or the gas generated at the target part of the X-ray source may be transferred to other parts. However, it is a further object of the present invention to eliminate this type of disadvantage.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings. FIG. 1 is a general view of an X-ray transfer apparatus constructed in accordance with the present invention. This X-ray transfer apparatus has a main chamber 1, a wafer load cassette storage chamber 2 and a wafer unload cassette storage chamber 3 arranged on both sides of the main chamber 1, and a wafer unload cassette storage chamber 3 also located on one side of the main chamber 1. It is composed of a mask cassette storage chamber 4, irradiation chambers 5a and 5b, and a subchamber 6 arranged side by side.

The main chamber 1 is a first main chamber portion 7 to which a loading storage chamber 2 and an unloading storage chamber 3 are respectively connected on both sides.
and a second main chamber part 8 to which a mask storage chamber 4 is connected on one side. The connection portions between the first main chamber portion 7 and each of the loading storage chamber 2 and the unloading storage chamber 3, and the connection portion between the second chamber portion 8 and the mask storage chamber 4 are independently vacuum-vacuumed. It is configured so that the state can be maintained.

The connection parts between the irradiation chambers 5a and 5b and each of the main chamber 1 and the subchamber 6 are also configured to maintain a vacuum state, and there are also holes between them for isolating each chamber from each other as needed. A gate valve 9 is arranged. For example, when it becomes necessary to replace or repair the X-ray tubes in the irradiation chambers 5a and 5b, the gate valve 9
By performing the work after closing the chambers 1 and 6, the vacuum state in the other chambers 1 and 6 can be maintained. This allows only the irradiation chambers 5a, 5b to be evacuated before restarting the operation of the X-ray transfer device after the work, and the required evacuation time can be extremely shortened. In addition, each chamber 1, 2, 3, 4, 5
A pipe 10 for connecting an evacuation vacuum pump (not shown) and each chamber is attached to the preferred surfaces of a, 5b, and 6.

Here, the main devices housed in the chamber and the operations performed in the chamber will be schematically explained with reference to FIGS. 2, 3, and 4. As shown in FIG. 4, the wafer load cassette storage chamber 2 has an
A device is provided for placing a cassette 13 containing a plurality of wafers 12 whose surfaces have been coated with photoresist in advance for transferring a circuit pattern using a line transfer device. This device is capable of raising and lowering the cassette 13 in the vertical direction and contributes to loading a plurality of wafers into the first main chamber portion 7 one after another.

A loading device for loading wafers one by one from a cassette 13 in the chamber 2 into the chamber 7 is disposed in the first main chamber portion 7 in close proximity to the chamber 2 . Further, a wafer parallel plane aligning device is arranged near the center in the length direction of the main chamber portion 7, and the wafer is aligned so that the surface of the wafer is parallel to the reference plane of the wafer holder supported on the irradiation table. Adjust and fix the position. In addition, at a position in the first main chamber portion 7 adjacent to the wafer unload cassette storage chamber 3, there is an unloading device for unloading the wafer, which has undergone the process of transferring a circuit pattern onto the entire surface of the wafer, into the chamber 3. It is provided.

Here, in the chamber 3, like the chamber 2, a device for placing a cassette 14 for storing wafers is arranged. This device has cassette 14
The wafers can be raised and lowered in the vertical direction, contributing to storing wafers that have been irradiated one by one into a cassette.

Next, the main devices and operations related to the mask storage chamber 2 and the second main chamber portion 8 will be explained with reference to FIG. The mask storage chamber 4 has a mask cassette 15 therein,
On the other hand, a plurality of masks 16 are held within this mask cassette 15. Further, according to the transfer process, a mask cassette 15 is used to index any mask 16 out of the plurality of masks to a mask take-out position.
A device for rotating the is also provided.

In the second main chamber part 8, adjacent to the mask chamber 4, a mask moving device is located which is used to remove the mask from the cassette or to return the mask to the cassette. A vertically movable mask handler for holding a mask holder is provided inside and above the second chamber portion 8. An optical microscope 17 for pre-alignment is attached to the upper part near the center in the length direction of the second chamber portion 8 for roughly aligning the mask and the wafer. On the other hand, a fine alignment electron microscope 18 is attached to the upper part of the second chamber portion 8 in close proximity to the prealignment optical microscope 17 for precisely aligning the mask and the wafer. Furthermore, a coarse and fine movement device that can move in the length direction of the chamber portion 8 is arranged inside the second chamber portion 8, and this coarse and fine movement device is used during pre-alignment and fine alignment to move the mask and Move the wafer position.

The main equipment and operations associated with the subchamber 6 are similar to those associated with the second main chamber section 8, except that it does not have a mask moving device used to remove the mask from the cassette or return the mask to the cassette. This is the same as the explanation given above.

Irradiation chamber 5 as shown in FIG.
A and 5b have X-ray tubes inside, and the mask and wafer are placed on a stand and are irradiated while moving as they pass through this chamber. At this time, the mask pattern is transferred to the wafer.

Here, the overall operation of the X-ray transfer apparatus will be schematically explained using an example in which a wafer is divided into four irradiation areas.

FIG. 5 shows a plan view of the mask 16, which has a circuit pattern 20 and a set of alignment marks 21 on an X-ray transparent substrate.
is made of an X-ray non-transparent material. The wafer shown in FIG.
The irradiation area is divided into four by 2 and 23. The irradiation is performed with the mask 16 superimposed on one of the four wafer irradiation areas, so the irradiation process must be performed four times to irradiate the entire surface of the wafer. Note that alignment marks may be formed in advance on the wafer side, and the alignment marks 24, 25, 2
6 are formed in each irradiation area.

Such alignment marks 24, 25, 2
A plurality of wafers 12 on which wafers 6 have been formed are stored in a wafer load cassette 13 in a stacked manner. Wafer 1
After the wafers 2 are taken into the chamber 7 one by one by a loading device, the position of the wafers is adjusted so that the orientation flat portion 27 of the wafers faces in a predetermined direction. Next, the wafer is transferred into a wafer holder supported on an irradiation table, and the wafer 12 is positioned using a parallel plane aligning device so that the surface of the wafer is parallel to the reference plane of the wafer holder and at a predetermined height. adjust. As a result, the opposing surfaces of the mask 16 held by the mask holder placed on the wafer holder and the wafer 12 are parallel and at a predetermined distance.

Here, the irradiation table on which the wafer is placed is moved to the central pre-alignment position of the second chamber portion 8.

On the other hand, the mask 16 taken out from the mask cassette 15 and fixed to the mask holder held by the mask handler is received together with the mask holder from the mask handler by the coarse and fine movement device. The coarse and fine movement device brings the mask holder onto the wafer holder on the irradiation table, which is waiting at the pre-alignment position, and overlaps the two. Here, the mask 16 and the first irradiation area of the wafer 12 are roughly aligned, and then the irradiation table is moved to an adjacent fine alignment position for more precise alignment.

The mask 16 and wafer 12, which have been precisely aligned in this manner, are placed on an irradiation table, transferred into the irradiation chamber 5a, and scanned and irradiated with X-rays. At this time, the second, third, and fourth irradiation areas of the wafer 12 are shielded so that areas other than the first irradiation area are not irradiated.

When the irradiation table passes through the irradiation chamber 5a and is transferred to the subchamber 6, the wafer irradiation area is switched. When the mask and the second irradiation area of the wafer are overlapped by the irradiation area switching operation,
Move the irradiation table sequentially to the pre-alignment position and fine alignment position. This allows coarse and precise alignment between the mask and the second irradiation area of the wear.

Next, in the same way as described above, the mask and wafer are placed on the irradiation table and transferred into the irradiation chamber 5b.
It is scanned and irradiated with X-rays. At this time, the first, third and fourth irradiation areas are shielded, and the second
Areas other than the irradiated area will not be irradiated.

When the irradiation table passes through the irradiation chamber 5b and is transferred to the second main chamber portion 8, the wafer irradiation area is switched again. In this way, the above-mentioned operation is repeated, and when the third and fourth irradiation areas of the wafer have been irradiated and the entire wafer has been irradiated, the irradiation table is moved from the second main chamber part 8 to the first chamber part 7. move it. Wafer 1 has the circuit pattern transferred to the entire surface of the wafer.
The wafers 2 are loaded into the wafer unload cassette 14 in the chamber 3 one by one by the unloading device. If the mask 16 needs to be replaced, the mask can be returned to the cassette 15 by the mask moving device, and another mask can be taken out from the cassette.

Although the irradiation process for one wafer has been described above, in the X-ray transfer apparatus of the present invention, a plurality of wafers 12 can be irradiated in parallel using a plurality of irradiation tables.

Next, in order to more clearly understand the overall operation of the above-mentioned X-ray transfer apparatus, important items will be explained in detail below.

(1) Loading, parallel plane alignment and unloading of wafers As shown in FIG. connected. Inside the loading chamber 2, a stand 30 is provided on which a wafer cassette 13 containing a plurality of wafers 12 coated with a resist that reacts with X-rays is placed. Supported by 31. The cassette 13 supported on the table is lowered vertically downward by the lifting device 31 each time one wafer is transferred into the first main chamber portion 7.

The wafers are transferred from the cassette 13 into the first main chamber portion 7 by a ware transfer device 32 shown in FIG. The loading device 32 loads the wafer 12 onto the top surface of the cassette 1.
3 and a sliding portion 35 for sliding the table 33 in the horizontal direction along a guide 34. The wafer 12 placed on the table 33 is moved above the wafer push-up device 36 by moving the sliding portion 35 . The push-up device 36 has a rotatable wafer support surface 37 and an orientation flat detector 38 mounted one step below this surface. Here, the lifting device 36 is driven to raise the wafer support surface 37, and the wafer 12 is received from the table 33 by this support surface 37. At this time, the position of the wafer 12 is determined by rotating the support surface 37 using the orientation flat detector 38 so as to direct the orientation flat 27 in a predetermined direction.

By driving the lifting device 36, the wafer 12 supported by the surface 37 is moved to the raised position.
The periphery of the wafer is held by a wafer hand 40 shown in FIG. This hand 40 has a guide 4
1, and a vertical cylinder 43 that is also movable up and down.
is also connected to.

The hand 40 is moved by sliding the sliding portion 42 along the guide 41 to a position above the wafer support surface 37, and is lowered by operating the vertical cylinder 43 at this position.
After receiving the wafer 12 from the support surface 37, the hand 40 operates the cylinder 43 again to ascend, and similarly moves the sliding portion 42 along the guide 41, thereby moving the wafer to a parallel plane position 44 (first position). Figure 4).

At this parallel plane position 44, the rail 4
An irradiation table 46 moving along lines 5 and 45 is waiting. As shown in FIG. 9, a wafer holder 47 is attached to the upper surface of this irradiation table 46, and inside the holder 47, an irradiation area moving table 48, a spherical surface A seat 49 and a wafer chuck 50 are arranged.

Openings 52 and 5 are provided at the bottom of the irradiation table 46 and the holder 47 for inserting the piezo element 51.
3 are formed respectively. This opening 52,
Preferably three 53 are formed. Preferably, three piezo elements 51 are vertically mounted on the upper surface of a vertically movable element support 54 facing the aforementioned opening.

On the other hand, a rod-like projection 55 is held at the bottom of the chuck 50 and is adapted to come into contact with the upper end of the element 51 inserted into the holder 47 through the openings 52 and 53. Further, the spherical seat 49 is fixed to the chuck 50, and a piezo element 56 for fixing the position of the spherical seat 49 abuts around the chuck 50.

A calibrator 58 is disposed at the parallel plane position 44 and is moved up and down by a lifting device 57 installed on the upper surface of the main chamber portion 7 . This calibrator 58 has a bottom plate 59
The bottom plate 59 has an opening 61 for inserting the gap sensor 60 and an opening 63 for inserting the chuck activation stage 62.

Here, as mentioned above, the parallel plane position 44
The wafer 12 carried by the hand 40 until
will be located between the wafer holder 47 and the calibrator 58, which are also waiting at the position 44. Next, the upper and lower cylinders 43 are operated to lower the wafer hand 40 toward the chuck 50, and when the wafer reaches near the top of the chuck 50, the hand 40 is operated to release the wafer and place it on the surface of the chuck 50. Wafer 12 is fixed to chuck 50 by electrostatic means.

After the hand 40 transfers the wafer 12 to the chuck 50, it is raised by the operation of the vertical cylinder 43, and is moved toward the chamber 2 by moving the sliding portion 42 along the guide 41.

A mechanism for aligning the wafer 12 fixed on the chuck 50 in a parallel plane will be explained. First, the lifting device 57 is operated to lower the calibrator 58 until the lower surface of its bottom plate 59 comes into contact with the upper end reference surface 65 of the holder 47.

Next, the element support base 54 is driven so that the piezo element 5
1 is raised through the openings 52 and 53, and the lower end surface of the rod-shaped projection 55 is pushed up. At this time, the gap sensor 60 is used to measure the distance between the upper surface of the wafer 12 and the upper end reference surface 65 of the holder 47. Fine adjustment is made up and down of the element 51 according to the measurement results, and when the wafer is aligned to a parallel plane, the element 56 is activated and brought into contact with the periphery of the spherical seat 49, and thus the chuck 5.
Fix the 0 position.

Next, the lifting device 57 is operated to move the calibrator 58 to the raised position, and the element support stand 54 is moved to the raised position.
Activate to move the piezo element to the lowered position. After that, the irradiation table 4 with the holder 47 placed on it
6 is moved from the parallel plane position 44 to the pre-alignment position along the rails 45, 45 by actuating a drive device (not shown).

Next, unloading of the wafer after irradiation will be explained. The wafer unload cassette storage chamber 3 has a cassette 14 for storing wafers, similar to the wafer load cassette storage chamber 2.
A table 30 is provided on which to place the table, and this table 30 is supported by a lifting device 31. The cassettes 14 supported on the table 30 receive the wafers from the first main chamber portion 7 and are sequentially raised vertically upward by the lifting device 31.

From the first main chamber part 7 to the cassette 1
The wafers are placed in the wafer 4 by using a wafer hand having the same configuration as shown in FIG. 8 and a wafer unloading device 66 shown in FIG. The device 66 has a base 67 and a sliding part 68.

As shown in FIG. 11, after the mask holder 70 is removed from the irradiation table 46 after irradiation by the holder hand 71, the irradiation table 46 advances toward the wafer hand along the rails 45, 45. Stop. Here, a wafer 1 is placed on a wafer chuck 50 by a hand.
The stand 6 of the wafer unloading device 66
7 Move to the top. With the wafer placed on the table 67, the sliding portion 68 advances toward the cassette 14 in the chamber 3 along the guide 69. By repeating the above procedure, the wafers that have been irradiated are sequentially stored in the cassettes 14 in the unload cassette storage chamber 3.

(2) Loading and unloading of masks Next, loading and unloading of masks will be explained with reference to FIGS. 3 and 11.

The lower lid 15b of the cassette 15 is lowered by operating the cassette lid opening device 72 for the mask cassettes 15a and 15b stored in the mask cassette storage chamber 4.

The cassette 15 has an upper lid 15a and a lower lid 15b.
It has a structure in which a plurality of masks 16 are held inside thereof on the upper lid 15a side by magnetic force.

The upper lid 15a of the mask can be rotated by driving the rotation device 74, and a desired one of the plurality of masks 16 described above can be indexed to the take-out position and storage position.

The chamber 4 is evacuated by opening the chamber 4 lid 75, storing the cassette 15 into the chamber 4, closing the lid 75, and then operating an exhaust device (not shown). When the degree of vacuum within the chamber 4 reaches a predetermined value, the previously closed slide valve 76 is opened and the mask moving member is inserted into the chamber 4 from the second main chamber portion 8 side. A claw is formed at the tip of the mask moving member to pull out the mask 16 which is magnetically held on the side of the upper lid 15a of the cassette. When the claw is brought into contact with the selected arbitrary mask 16, the upper lid 15a is raised by operating the upper lid elevator 74b, the mask 16 is removed from the upper lid 15a, and the mask is moved toward the inside of the second main chamber portion 8. The member is retracted and the mask 16 is moved from within the chamber 4 to the mask stage 77 within the main chamber portion 8.

The mask stage 77 includes a mask handler 78 for holding the mask 16 and a mask position sensor 79 for detecting the position of the mask.
Furthermore, a mask pushing device 80 is provided for pushing up the mask held by the mask handler 78 vertically upward.

The mask handler 78 is mounted on a moving member to hold the mask positioned on the stage 77, and can rotate to position the mask in response to the detection of the mask position by the sensor 79.

After accurate positioning of the mask is completed in this way, the mask handler 78 moves the mask 1
6 and operate the push-up device 80,
Move the mask handler 78 vertically upward.

Here, the sensor 79 is movable in the horizontal direction and is positioned above the mask held by the handler 78 when detecting the position of the mask, and returns to its original position after the correct positioning of the mask is completed. When the mask handler 78 is moved in the vertical direction, it does not become an obstacle.

A mask holder hand 71 is arranged vertically above the mask stage 77. This mask holder hand 71 has contact members 81 and 8 for sandwiching the mask holder 70 from both sides.
1 and the mask holder 70 with contact members 81, 81
It is composed of shaft members 82, 82 for moving up and down while being sandwiched between them.
The shaft members 82, 82 are moved up and down by a lifting device 83 installed at the upper part of the main chamber portion 8. Further, the contact members 81, 81 are rotatably connected to the shaft members 82, 82, and rotate when receiving the mask holder 70 sent after irradiation. is passed to a position where it abuts against one of the abutting members 81. Thereafter, the abutment member 81, which had been rotated and moved away from the movement path of the mask holder 70 as described above, is rotated again, and the holder 70 is held between the two abutment members 81, 81.

The mask holder 70 held by the hands 71 in this manner has a mask handler 78
opening 8 for partially accommodating the mask moving vertically upward while being held by the
4, and a magnetic body buried in the bottom to hold the mask with magnetic force. Therefore, the mask held by the handler 78 and moved vertically upward by the mask push-up device 80 is held by the mask holder 70.
On the other hand, the handler 78 releases the mask and descends vertically downward by the operation of the rear mask lifting device 80.

Next, contrary to the above, the mask holder 70
The procedure for storing the mask 16 held by the mask cassette 15 into the mask cassette 15 will be explained.

First, the push-up device 80 is activated to move the mask handler 78 to the vicinity of the mask 16 held below the mask holder 70. Then, the handler 78 is activated to clamp the periphery of the mask. Here, the magnetic material provided at the bottom of the holder 70 is demagnetized. In this way, the holder 70
After pulling the mask off, push up device 80
is driven to move the mask vertically downward while being held by the handler 78.

Next, the mask held by the handler 78 and positioned on the mask stage 77 is received by a claw formed at the tip of the mask moving member. At this time, when the claw receives the mask, it activates the handler 78 so that it can be removed from the mask. Thereafter, the mask moving member is moved so as to be inserted into the chamber 4, and the tip thereof is positioned between the upper lid 15a and the lower lid 15b of the cassette 15. Here, using the magnetic material provided on the upper lid 15a of the cassette, the mask 16 located at the tip of the mask moving member is attracted to the lower surface of the upper lid 15a.
Hold.

(3) Irradiation table and moving table The moving table and irradiation table will be explained using Figure 12. In the figure, 85 is a moving platform, and the vertical moving rail 8
6 and 86 by a drive device (not shown). The vertical movement rails 86, 86 are the movement platform 85
has a length that allows movement between the fine alignment position A and the mask attachment/detachment position C. Mobile platform 8
Lateral movement rails 45, 45 are fixedly installed on 5,
The irradiation table 46 freely moves on the lateral movement rails 45, 45. One end of the lateral movement rails 45, 45 is located at the fine alignment position A of the irradiation table 46.
is connected to the relay rails 87, 87,
The other end is determined to occupy a wafer load position D and a wafer unload position E when the irradiation table 46 moves on the lateral movement rail. That is, the movable table 85 is at the pre-alignment position B, and the irradiation table 46 is moved from that position to the lateral movement rail 4.
5, 45, the wafer load position D can be reached. Further, the moving table 85 is at the mask attaching/removing position C, and when the irradiation table 46 moves on the rails 45, 45 from that position, it reaches the wafer unloading position E. A member 47 held by a magnetic chuck on the irradiation table 46 is a well holder, and is provided with a square recess, in which the irradiation area moving table 48 can be moved. The relative movement between the wafer holder 47 and the irradiation area moving table 48 will be described later. A wafer chuck 50 is provided on the table 48 to chuck wafers.

FIG. 6A A coarse and fine movement device 88 movable in the lateral direction shown in FIG. 13 is arranged above the moving table 85 and the irradiation table 46. This coarse/fine movement device 88 is used to align the mask and the wafer, and is guided by other lateral movement rails 89, 89 provided parallel to the lateral movement rails 86, 86.

FIG. 14 depicts details of the coarse and fine movement device 88. 90 is a coarse and fine movement frame, and lateral movement rails 89, 8
9 is hung from the penetrating beam at four locations, and compression springs for absorbing collision energy are inserted between the two to fix the frame below. A mask holder 70 and a wafer holder 4 are placed inside the frame.
7 is a moving platform push-up mechanism (not shown) (details will be described later)
It is pushed up and enters. Coarse movement mechanisms 91a, 91b, etc. supported by laminated piezo elements are provided outside the coarse and fine movement frame 90, and push rods 92a of the coarse movement mechanisms 91a, . . . project into the inside of the frame 90. The coarse movement mechanism 91a is the fifteenth
As shown in the figure, the rotational force of the coarse motor 93a is converted into linear movement of the push rod 92a by a combination of a rack and pinion, for example. The bearing of the push rod 92a is formed by a V-shaped block 94a and a cantilevered leaf spring 95a that presses the push rod 92a from above. The leaf spring 95a is further pressurized by a piezo element rod 96a, and when the piezo element rod 96a is energized, the push rod 92a is pressed against the leaf spring 9.
5a and clamped to block 94a. 97, 97 are stacked piezo elements having the function of moving the coarse movement mechanism 91a back and forth by a minute amount, one end of which is fixed to the coarse movement mechanism 91a, and the other end fixed to the outside of the coarse and fine movement frame 90. Further, coarse movement mechanisms 91b similar to those described above are fixed to the outside of the coarse and fine movement frame 90 using stacked piezo elements.

Next, coarse and fine adjustment will be explained using FIG. 16. In the figure, 92a to 92e are coarse and fine movement frames 90.
The push rods 92f to 92j abut the mask holder 70 with the push rods protruding from the upper stage, and the wafer holder 47 with the push rods 92f to 92j protruding from the lower stage. That is, push rods 92a and 92b
is in contact with one side of the mask holder 70, the push rod 92d is in contact with the opposite side to clamp the mask holder 70, and the left and right sides are respectively in contact with and clamp the push rod 92c and 92e. Wafer holder 47
Similarly, push rods 92f and 92h and 92i face each other, and push rods 92g and 92j face each other to hold them. For example, when adjusting the X, Y, and θ of the mask holder 70, the push rods 92c and 92e are slightly loosened for adjustment in the
This is achieved by pushing out and drawing d into each other.
At this time, in the initial state, the coarse adjustment motor 93a is driven to move the push rod 92a back and forth for rough adjustment, and then the piezo element rod 96a is driven to clamp the push rod 92a. Next, when the stacked piezo elements 97 are energized, the entire coarse movement mechanism 91a moves back and forth minutely to move the mask holder 7
The position of 0 can be precisely positioned.
Further, for adjustment in the Y direction, the push rods 92e and 92c can be pushed and pulled against each other for positioning.

On the other hand, when adjusting the θ direction, use the push rod 9.
Slightly loosen 2c and 92e, push rod 92
By changing the protrusion amount of the push rod 92b and the push rod 92b, the mask holder 70 will rotate around the tip of the push rod 92d. The position of the wafer holder 47 can also be adjusted in the same manner as described above.

(4) Pre-alignment and fine alignment Returning to FIG. 12, pre-alignment and fine alignment will be explained. First, at the mask attachment/detachment position C, a step of attaching the mask holder 70 with the mask attached to the coarse/fine movement device 88 is performed. Therefore, after once lowering the mask holder hand 71, the coarse and fine movement device 88 is moved to the mask attaching/detaching position C, and the coarse and fine movement device 88 is aligned above the mask holder 70. Next, the mask holder hand 71 is raised to fit the mask holder 70 into the coarse and fine movement frame 90 of the coarse and fine movement device 88, and the push rods 92a to 92e are made to protrude and hold the mask holder 70.

On the other hand, when a wafer is mounted on the wafer chuck 50 at the wafer load position D and the above-described parallel plane alignment process is completed, the irradiation table 46 moves on the lateral movement rails 45 and is located at the pre-alignment position B. At this time, the coarse and fine movement device 88 moves along the vertical movement rails 89, 89 (FIG. 13), stops at the pre-alignment position B, and is aligned with the wafer holder 47.

With the irradiation table push-up mechanism 98 shown in FIG.
The irradiation table 4 is moved using a push-up rod with three claws through an opening (not shown) made in the center of the movable table 85.
6 and raise the reference planes 46a and 46 of the irradiation table 46.
b is pressed against the reference lower surface of the frame 90 of the coarse and fine movement device to determine the height and perform equalization.

FIG. 17 depicts a state in which the mask holder 70 and the wafer holder 47 are connected by an electrostatic chuck (not shown).
Since the distance from the (reference plane) has been determined,
If the mask holder 70 is brought into accurate contact with the lower end surface (reference surface), the lower surface of the mask 16 and the surface of the wafer 12 will be set extremely close to each other with an interval of about several microns. Here, the irradiation table 46 and the wafer holder 4
The magnetic chuck 99 between 7 and 7 is released, and the mask and wafer are aligned in accordance with the operations described above using FIG.

The alignment mark on the wafer is placed on the scribe line in order to make effective use of the wafer, but on the other hand, the final alignment between the mask and the wafer requires an accuracy of 0.1 micron or more, so in this example, a scanning type is used. Realized using an electron microscope. Therefore, when alignment is performed, the alignment mark on the wafer is scanned with an electron beam, but if the electron beam swings more than the scribe line width, there is a problem that the area where the actual device is to be formed will be irradiated. Therefore, unless the alignment mark is placed in an occupied area or the actual element spacing is larger than the mechanical initial setting accuracy, the degree of alignment between the mask and wafer should be kept to an error on the order of 10 microns. is desirable.

FIGS. 18 and 19 are diagrams schematically showing the configuration of an optical microscope 17 for pre-alignment. This optical microscope 17 is composed of two microscopes that detect alignment marks 21, 21 on the mask 16 and two microscopes that detect alignment marks 26, 26 on the wafer 12 (see FIG. 18). (Only one of each is shown). Each of the four microscopes has an objective lens system of 1.
00, imaging lens system 102, TV imaging device 10
It has 3. As described above, the positions of the mask holder 70 and the wafer holder 47 are adjusted independently by the coarse and fine movement device 88, and the alignment marks 21, 21 of the mask 16 and the alignment mark of the wafer 12 are adjusted by the scale plate 101.
is aligned with the reference mark. When the pre-alignment of the mask and wafer is completed, the mask holder 7
0 and wafer holder 47 are coupled together by an electrostatic chuck, and push loads 92a to 92j of coarse and fine movement device 88 separate from mask holder 70 and wafer holder 47 to release them. Subsequently, the push-up rod of the irradiation table push-up mechanism 98 descends,
The irradiation table 46 is grounded on the movable table 85.

Here, when the moving table 85 checks the irradiation table 46, the moving table 85 moves to the fine alignment position A. At this time, the coarse and fine movement device 88 has also moved to the fine alignment position A, and the irradiation table push-up mechanism 104 at the fine alignment position A operates to push up the irradiation table 46. It is preferable that the push-up mechanism 104 be moved up and down by a cam, for example, so that the acceleration becomes zero at the highest raised position, thereby avoiding a sudden collision between the mask holder 70 and the wafer holder 47.

Push rods 92a to 9 of coarse and fine movement device 88
2j is the mask holder 70 and wafer holder 4 again.
7 and the fixing magnetic force between the mask holder 70 and the wafer holder 47 and between the wafer holder 47 and the irradiation table 46 is eliminated, and then the fine alignment electron microscope 18 detects the alignment mark.

FIG. 20 shows a schematic diagram of the fine alignment electron microscope 18. The fine alignment electron microscope 18 has four scanning electron microscopes that operate independently, two of which are connected to the mask 1.
6 alignment marks 21, 21 are detected,
The other two pass through the window 105 of the mask holder 70 and align the alignment marks 26, 26 on the wafer 12.
(Only one of each is shown in FIG. 20).
Note that this window 105 is designed to be closed when the wafer is irradiated with the irradiation chambers 5a and 5b.

An electron gun 106 generates an electron beam. 1
07 is a condenser lens, 108 is an objective lens, and 109 is an electrostatic deflector that swings an electron beam in two-dimensional directions. A two-dimensional scanning electron beam passes through a slit in a reference plate 110 into a mask 16.
and to alignment marks on wafer 12. Backscattered electrons from the mask and wafer are detected by a backscattered electron detector 111, and based on this detection signal, the alignment marks of the mask and wafer are moved to the center of the slit of the reference plate 110.

At this time as well, the push rods 92a to 92j of the coarse and fine movement device 88 regulate the positions of the mask holder 70 and wafer holder 47, and each alignment mark is made to coincide with the axis of the corresponding electron microscope, thereby completing the fine alignment.

When the fine alignment of the mask and wafer is completed, the mask holder 70 and the wafer holder 47
are connected by a magnetic chuck. Push rods 92a to 92j of coarse and fine movement device 88
moves away from the mask holder 70 and wafer holder 47 to release them. After the wafer holder 47 and the irradiation table 46 have been chucked, the push-up rod of the irradiation table push-up mechanism 104 descends, and the irradiation table 4
6 is grounded on the moving table 85 and both are checked.

(5) Irradiation Next, the irradiation section will be explained using Figures 1 and 2. The irradiation section is installed in a vacuum chamber independent from the others, and is connected to the main chamber 1 and subchamber 6 via airtight gate valves 9 and bellows-like universal joints 112 and 112. The gate valve 9 is normally open, but if, for example, it is necessary to repair the inside of the irradiation section, it is closed to maintain the vacuum in other chambers such as the main chamber 1.

The X-ray irradiation system consists of an X-ray tube 113 and solar slits 114a and 114b.
is the target 11 extending perpendicularly to the screen in Figure 2.
5 and a long electron gun 1 placed diagonally above it on both sides.
16, 116 and a deflection plate 117. The deflection plate 117 has the function of deflecting the electron beams generated by the electron guns 116, 116 and guiding them to the bottom of the target 115. Note that the lengths of the electron gun and the target are determined to be slightly longer than the width of the mask to be irradiated.

Reference numerals 114a and 114b each represent a solar slit, which acts as a collimator to extract parallel components of the radial soft X-rays generated from the target 115. This solar slit is, for example, a glass or metal plate with a thickness on the order of a millimeter and equipped with countless microscopic holes on the order of 10 microns. blocks the components of Multiple solar slits are arranged depending on the degree of parallelism, and the masks that require high resolving power are irradiated with soft X-rays with good parallelism, and when using a mask that does not require very high resolving power, they are slightly parallel. Even if the intensity is lowered, the irradiation amount can be increased and the irradiation time can be shortened. 11
Reference numeral 8 denotes a switching mechanism for the Solar slit, which allows switching from outside the housing between the Solar slit 114a, which provides soft X-rays with high parallelism, and the Solar slit 114b, which provides normal parallelism, without lowering the vacuum. I'm doing it like that.

Next, 87 is the relay rail drawn in Figure 12,
It extends inside the gate valves 9 and 9 and is connected to the irradiation table 46.
helps to move the wafer holder and mask holder at a constant speed, i.e., the mask and wafer are held in close proximity while crossing a parallel beam of soft X-rays extending in a direction perpendicular to the drawing. The mask will be scanned and the entire surface of the mask will be irradiated.

(6) Irradiation area movement When irradiation is completed, the irradiation table 46 moves to the irradiation area movement position F. As shown in FIG. 12, another moving platform 85 is arranged, and the vertical moving rail 11
It is designed to be able to move on 9,119. Above the moving table 85 are horizontal moving rails 120, 120.
is provided, and when the moving table 85 moves, it moves together with it. These members are housed in an airtight subchamber 6. This subchamber 6 is also provided with a pre-alignment device, a fine alignment device, etc.
It has a similar structure to the main chamber 1 except for the parts for attaching and removing masks and wafers.

The second movable table 85 in FIG.
comes to the terminals of the relay rails 87, 87, the lateral movement rails 120, 12 are placed on the extension of these rails.
It is stationary at the position where 0 is aligned. 71 is the second
The mask holder hand has the function of grasping the mask holder 70 and lifting it from the wafer holder 47 similarly to the mask holder hand described above.

At the irradiation area movement position F, in addition to the second mask holder hand 71, an irradiation area movement lift is arranged. In FIG. 21, the irradiation table 46, the horizontal movement rails 120, 120, the movement table 85, and the vertical movement rails 119, 119 are as described above. On the other hand, the second moving table 85 has an opening in the center, and a recessed fixture 121 is provided in the opening. Laminated piezo elements 122a and 122b are attached to this fixture 121, and a solenoid 123a is further attached to the top of the piezo elements 122a and 122b.
and 123b are provided, respectively.

On the other hand, a suction plate 124 whose lower surface is made of a magnetic material is fixed to the bottom of the irradiation area moving table 48 via a support, and the support is connected to the wafer holder 4.
7 and the opening made at the bottom of the irradiation table 46, and the suction plate 124 can move within the opening.
After eliminating the magnetizing force between the irradiation area moving table 48 and the wafer holder 47, when the piezo element 122a is energized, the piezo element expands and the solenoid 123a
The head of the wafer holder pushes up the suction plate 124, so that the irradiation area moving table 48 is separated from the wafer holder 47 by about two to three hundredths of a millimeter. At this stage, if the solenoid 123a is actuated to fix the irradiation area moving table 48 to the moving table 85 and the irradiation table 46 is sent a specified distance along the lateral movement rails 120, 120, the wafer holder 47 will also move along with the irradiation table 46. Since it moves, the irradiation area moving table 48 has moved relative to the wafer holder 47. In other words, the irradiation area has been changed.

Thereafter, when the power supply to the solenoid 123a is stopped and then the power supply to the piezo element 122a is stopped, the piezo element 122a contracts and the irradiation area moving table 48 is grounded on the wafer holder 47. When the irradiation area moving table 48 and the wafer holder 47 are attracted to each other again, the preparation for movement to the second pre-alignment position G is completed. In addition, the other set of piezo element 122b and solenoid 123b has two irradiation stands.
It is used to move the irradiation area when it comes to the second visit. Thereafter, the same operations as described above are repeated. That is, the mask holder 70 is held by the second coarse/fine movement device (not shown) and moved to the pre-alignment position G.
At that position, the wafer holder 47 is combined with the wafer holder 47 placed on the moving table 85 for pre-alignment, and after fine alignment, irradiation is performed.

The movement of the irradiation area is also performed at the wafer unload position E. Reference numeral 125 shown in FIG. 4 is an irradiation area moving lift, and its operation is the same as that of the lift described above. In FIG. 22A, a stacked piezo element 127 and a solenoid 128 are mounted on a shaft 126 mounted on the lower surface of the chamber 7. As the piezo element 127 expands, the solenoid 128 pushes up the suction plate 124. After that, as shown in FIG. 22B, the irradiation table 46
The wafer holder 47 and the moving stage 85 are moved along the vertical moving rail 86. As a result, the position of the irradiation area moving table 48 can be displaced with respect to the wafer holder 47. Next, the power supply to the solenoid 128 and the piezo element 127 is cut off, and the irradiation area moving table 48 and the wafer holder 47 are connected.

In the embodiment described above, the irradiation chambers 5a and 5b arranged along the circulation path were each equipped with its own X-ray tube. It can also be replaced with a chamber.

In FIGS. 23A and 23B, 115' is a target, and 116' and 116' are electron guns. The electron beams emitted from the electron guns 116', 116' hit the target 115' and emit soft X-rays. 11
4' and 114'' are solar slits placed within the X-ray divergence angle, and their action is the same as described above.However, solar slits 114', 114''
4'' is tilted, it is necessary to scan with the irradiation table 46 tilted inward.
In this example, a tilting table 13 that can be tilted as a whole centering on the inner rail of the relay rails 87, 87.
0, and when the irradiation table 46 transfers from the lateral movement rail 45 to the relay rail 87, these are tilted. When the scanning is completed, the irradiation table 46 is returned to the horizontal state to enable it to be transferred to the next lateral movement rail 120. In addition, the remaining solar slit 1
The conveyance path passing under 14'' has a similar configuration, and if an irradiation chamber containing these is connected between the main chamber 1 and the subchamber 6, a transfer device can be constructed.

Further, in the embodiment shown in FIG. 1, one irradiation chamber is arranged between the main chamber 1 and the subchamber 6, but two or more irradiation chambers may be arranged in each case. In this way, it is possible to increase the scanning speed, or even if one of the X-ray tubes fails, the remaining tubes can be used to continue the irradiation process.

Furthermore, the wafer load cassette storage chamber 2 is kept on standby not only to prevent the high vacuum inside the main chamber 1 from being violated by the outside world, but also for a sufficient period of time to sufficiently release the gas occluded on the surface of the wafers brought in from the outside world. I'm letting you do it. However, if the wafer is transported from the resist coating equipment in the previous process into a large tube whose interior is maintained in vacuum, chamber 2 is used to adjust the difference in the degree of vacuum between the transport tube and the main chamber. or may be omitted.

As explained above, in the X-ray transfer apparatus of the present invention, since there is no member such as a window for deriving energy between the energy generation source and the mask, the mask is irradiated extremely effectively, and the amount of power supplied to the X-ray generation source is High throughput can be achieved by reducing the irradiation time or by shortening the irradiation time.

In the above-described embodiment, the mask and wafer are left in the vacuum of the cassette storage chamber before being carried into the main chamber, so the occluded gas in the mask and wafer is released within this chamber, and therefore the gas in the main chamber is The degree of vacuum is not disturbed. In addition, a partition wall with a solar slit is placed between the mask and the target of the irradiation system, and the opening of the solar slit is extremely small, so that gas generated near the target will not have an adverse effect on the mask side. do not have.

[Brief explanation of the drawing]

1 is a plan view of an X-ray transfer device constructed according to the present invention, FIG. 2 is a view taken along the line - in FIG. 1, and FIG. 3 is a view taken along the line - in FIG. Figure 4 is a diagram along the - line of Figure 1, Figure 5 is a diagram along the - line of Figure 1,
Figure 6 is a plan view of the mask, Figure 6 is a diagram showing the state in which the mask and wafer are stacked, Figure 7 is a schematic diagram of the wafer loading device, Figure 8 is a schematic diagram of the wafer hand, and Figure 9
The figures are for explaining the wafer parallel plane alignment mechanism, Figure 10 is a schematic diagram of the wafer unloading device, and Figure 11 is a schematic diagram of the wafer unloading device.
The figure is a diagram for explaining wafer unloading, Figure 12 is a diagram for irradiating the moving table and irradiation table, Figure 13 is a perspective view of the coarse and fine movement device, and Figure 14 is a detailed view of the coarse and fine movement device. , FIG. 15 is a detailed diagram of the coarse movement mechanism, and FIG. 16 is a diagram for explaining coarse and fine adjustment.
Figure 17 is a diagram showing the state in which the mask holder and wafer holder are stacked, Figure 18 is a schematic diagram of the optical system of an optical microscope for pre-alignment, and Figure 19 is an optical microscope for pre-alignment, showing the state in which the mask and wafer are overlapped. FIG. 20 is a schematic diagram of an electron microscope for fine alignment, FIG. 21 is a diagram for explaining the irradiation area movement at the irradiation area movement position F, and FIGS. 22A and 22 are diagrams showing the alignment state. B
23A and 23B are diagrams each showing a configuration for irradiating a plurality of masks with one X-ray source. , FIG. 24 is a diagram showing the relationship between X-ray intensity and energy. 1... Main chamber, 2... Wafer load cassette storage chamber, 3... Wafer unload cassette storage chamber, 4... Mask cassette storage chamber, 5a, 5b... Irradiation chamber, 6...
Subchamber, 12...wafer, 16...mask.

Claims (1)

[Scope of Claims] 1. An X-ray transfer device that exposes and transfers a pattern formed on a mask onto a wafer by irradiating the mask and the wafer with X-rays, the apparatus comprising: the mask and the wafer housed therein; It has an irradiation chamber for irradiating a mask and wafers with X-rays generated from an X-ray source, and a storage section for storing a plurality of wafers in a reduced pressure state;
An X-ray transfer apparatus comprising: a storage chamber whose interior can be depressurized independently of the irradiation chamber; and a transport mechanism that transports a wafer between the irradiation chamber and the storage chamber. 2. An X-ray transfer device that exposes and transfers a pattern formed on a mask onto a wafer by irradiating the mask and wafer with X-rays, with the mask and wafer housed inside and with the inside under reduced pressure. , has an irradiation chamber for irradiating a mask and wafer with X-rays generated from an X-ray source, and a storage section for storing a plurality of masks;
An X-ray transfer apparatus comprising: a storage chamber whose interior can be depressurized independently of the irradiation chamber; and a transport mechanism that transports a mask between the irradiation chamber and the storage chamber.