JPS60178112A - Wafer transferring device - Google Patents

Abstract

PURPOSE:To transfer stably a wafer without damaging the surface thereof in a wafer transferring device suited for a semiconductor manufacturing apparatus by providing a bed capable of locating and mounting the wafer on a slide portion slidable along a guide. CONSTITUTION:A wafer transferring device 32 for transferring wafer 12 from a cassette to a main chamber (both not shown) in a semiconductor manufacturing apparatus, particularly a X-ray transfer apparatus has a bed 33 for withdrawing from a cassette 13 the wafer 12 received in the cassette 13 and mounted on the upper surface of the bed. This bed 33 is attached to a slide 35 slidable horizontally along a guide 34 and driven by a drive unit 40. Also, the bed 33 is formed with a shoulder 41 abutting against a portion of the periphery of the wafer 12 so that the wafer 12 in the cassette 13 can be hooked and withdrawn by the shoulder 41. And the wafer 12 reaching above a wafer lifting device 36 is received and lifted by a support surface 37.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wafer conveyance device conveniently used in semiconductor device manufacturing equipment and eKX-ray transfer equipment.

As the degree of integration of circuits increases, the width of lines constituting circuit patterns is required to be on the order of microns and submicrons.

To achieve this, the irradiation energy used to transfer the circuit pattern is ultraviolet, far ultraviolet, and soft X-rays, all of which have increasingly shorter wavelengths.

Efforts have already been made to commercialize lithography equipment that uses soft X-rays for more than 10 years.

X for the production of semiconductor devices, which is still practical even today.
The line transfer device has not yet been completed. This is due to printing resolution, alignment accuracy, throughput, etc., which are requirements for practical use.
This is thought to be due to insufficient balance or optimization of equipment reliability, operability, equipment price, etc.

However, when we examine the requirements for realizing an X-ray transfer device in more detail, one of the problems is that handling soft X-rays is much more difficult than that of visible light or ultraviolet light. Since soft X-rays must be generated in a vacuum container, the soft X-rays are extracted through a beryllium foil window in the vacuum container in order to irradiate the mask and wafer that are placed in close proximity or close contact. Beryllium was selected because it has an extremely low absorption ratio of soft When the thickness of beryllium foil reaches this level, the absorption rate of soft Xa becomes as high as 50%, which is disadvantageous.

Furthermore, in addition to this, the following difficulties were noted by the inventors of the present invention. FIG. 9 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 line III with the lower right corner 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 area on the left side of the dotted line is absorbed by beryum, so the energy actually used for irradiation is approximately 4KeV. It is just the area between the position and the dashed line.

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

Another problem arises from irradiating the mask with divergent soft x-rays. If the mask and wafer are kept in close proximity and are hit by diverging soft X-rays, and if the wafer were to tilt, the dimensions of the mask image would change between the area where the mask and wafer approached and the area where they moved away. Change. Therefore, although it is necessary to strictly maintain parallelism between the mask and the wafer, it is extremely difficult to achieve this mechanically. In addition, when irradiating with a single divergent beam, the dimensions of the mask image differ between the center and the periphery, so not only must the mask and wafer be aligned each time, but the center of the mask and the axis of the Xa source must be accurately aligned. It is necessary to match.

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- 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 without affecting the pattern image.

Historically, in conventional semiconductor manufacturing equipment, a rubber belt has been used as a conveying means for taking out wafers from a wafer cassette and supplying them to a wafer stage. However, when this rubber belt is applied to an XfIM transfer device, the following problems occur.

If a wafer conveying means such as a rubber belt is used in an X-ray transfer device that handles wafers in a vacuum, the degree of vacuum within the device cannot be maintained due to gas molecules released from the rubber belt itself. Furthermore, with X-ray transfer devices, attempts are being made to realize transfer in the submicron region. Dust such as abrasion powder generated between the rubber belt and the pulley supporting it causes defects in the transferred image, which obstructs the purpose of submicron transfer.

In addition, a wafer conveyance device using a rubber belt has a structure in which wafers are conveyed sequentially from the bottom end of the wafer cassette, and wafers located in the center of the wafer cassette cannot be conveyed in a timely manner. In an X-ray transfer apparatus that uses a plurality of masks, it is necessary to perform transfer using the most suitable combination of masks and wafers, and it is desirable to be able to take out appropriate wafers from the wafer cassette at any time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer transport device that can be conveniently used in semiconductor manufacturing equipment, particularly in X-ray transfer equipment.

The wafer transport device of the present invention can transport any wafer in a wafer cassette without causing the problem of emitting gas into a vacuum unlike a rubber belt. Furthermore, the wafer can be transported without touching anything on the surface of the wafer to be transferred. Furthermore, since the wafer is held by the steps, it is easy to locate the center of the wafer, and the time required for orientation flat detection VC can be shortened.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings. FIG. 1 is an overall view of the X-ray transfer device. This X# transfer device consists of a main chamber 1, a wafer load cassette storage chamber 2 and a wafer unload cassette storage chamber 3 respectively arranged on both sides of the main chamber 1, and a wafer unload cassette storage chamber 3 on one side of the main chamber 1. A mask cassette storage chamber 4 arranged in line with the chamber 3 and an irradiation chamber 5
a, 5b, and a subchamber 6.

The main chamber 1 includes a first main chamber part 7 to which a loading storage chamber 2 and an unloading storage chamber 3 are connected on both sides, and a second main chamber part 7 to which a mask storage chamber 4 is connected to one side. It consists of a chamber part 8. 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 independent from each other. It is constructed to maintain a vacuum state.

The connecting portions 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.

Further, a gate valve 9 is arranged between the two to separate the chambers from each other according to convenience.

For example, if it is necessary to replace or repair the X-ray tubes in the irradiation chambers 5a and 5b, close the gate valve 9 before starting the work. A vacuum state can be maintained. This is K, after work
irradiation chamber 5a before starting operation of the line transfer device again.
, 5b only need to be evacuated, and the required evacuation time can be extremely shortened. Furthermore, each chamber is 1゜2,
A pipe 10 for connecting an exhaust vacuum pump and each chamber is attached to a preferred surface of each chamber.

Here, we will explain the main parts of the equipment housed in the chamber and the operations carried out in the chamber described above.
This will be schematically explained with reference to FIGS. 3 and 4.

As shown in FIG. 4, the wafer load cassette storage chamber 2 includes a cassette 13 containing a plurality of wafers 12 whose surfaces have been coated with photoresist in advance for transferring circuit patterns using an XIIJ transfer device. A running device is provided for placing the. 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 part 7 one after another.

Inside the first main chamber part 7 is a wafer transport according to the invention for transporting wafers one by one from the cassette 13 in the chamber 2 into the chamber 7 .

An input device is located adjacent to the chamber 2.

Furthermore, a wafer parallel plane aligning device is disposed near the center in the length direction of the main chamber portion 7, and is used to align the wafer surface parallel to the reference plane of the wafer holder supported on the irradiation table. Adjust and fix the wafer position. Also, a position ffK in the first main chamber portion 7 adjacent to the wafer unload cassette storage chamber 3 is an unloading device for unloading the wafer into the chamber 3 after the process of transferring the circuit pattern onto the entire surface of the wafer. is provided.

Here, chamber 3 is the same as L chamber 2.

A device is provided for placing a cassette 14 for storing wafers. This device can move the cassette 14 up and down, and contributes to storing wafers that have been irradiated one by one into the cassette.

Next, referring to FIG. 3, the mask storage chamber 4 and the second
The main equipment and operations related to the main chamber section 8 will be explained. The mask storage chamber 4 has a mask cellar) 15 therein, while this mask cellar) 15
A plurality of masks 16 are held inside. Furthermore, a mask cassette 15 is used to index any mask 16 out of the plurality of masks to a mask removal position according to the transfer process.
A device for rotating the is also provided.

In the second main chamber part 8, in close proximity to the mask chamber 4, a mask moving device is located which is used when removing the mask from the cassette or returning the mask to the cassette. Inside and above the second chamber portion 8 is a vertically movable mask handler for holding a mask holder. At the upper part near the center in the length direction of the second chamber part 8 is an optical microscope 17 for pre-alignment for rough alignment of the mask and the wafer.
is installed.

On the other hand, the upper part of the second chamber portion 8 is located close to the optical microscope 17 for pre-alignment.

A fine alignment electron microscope 18, which is used to closely align the mask and wafer, is shown. Furthermore, a coarse and fine movement device that can move along the length of the chamber portion 8 is arranged inside the second chamber portion 8, and is used to move the mask and wafer during pre-alignment and fine alignment. Move the position of.

The main equipment and operations associated with the subchamber 6, except that it does not have a mask transfer device used to remove the mask from the cassette or return the mask to the cassette.

The description is similar to that given above in connection with the second main chamber part 8.

The irradiation chamber 5a shown in FIG.

5b has an X-ray tube inside, and the mask and wafer are placed on a stage and 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, taking as an example a case 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 formed on an X-ray transparent substrate using an xffM non-transparent material. . The irradiation area of the wafer shown in FIG. 6 is divided into four by orthogonal holes 22 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 one set of alignment marks 24, 25, and 26 are formed in each irradiation area.

A plurality of wafers 12 having alignment marks 24, 25, 26 formed thereon are stored in the wafer load cassette 13 in a stacked manner. After the wafers 12 are taken into the chamber 7 one by one by the loading device, the positions of the wafers are 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 the irradiation table, and the wafer 12 is placed so that the surface of the wafer is parallel to the reference plane of the wafer holder and at a 'predetermined' height using a parallel plane aligning device. Adjust the position. 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 spaced apart from each other by 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.

Meanwhile, the mask is taken out from the mask cassette 15.

The mask 16 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. At this point, the mask 16 and the first irradiation area of the wafer 2 are roughly aligned, and then the irradiation table is moved to an adjacent fine alignment position for more precise alignment.

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

When the irradiation table passes through the irradiation chamber 5a and is transferred to the subchamber 6, the wafer irradiation area is switched. After the mask and the second irradiation area of the wafer are overlapped by the irradiation area switching operation, the irradiation table is sequentially moved to the real alignment position and the fine alignment position.

This provides coarse and fine alignment between the mask and the second irradiation area of the wafer.

Next, in the same manner as described above, the mask and the wax are placed on an irradiation table and transferred into the irradiation chamber 5b, where they are scanned and irradiated with X-rays. At this time, the first, third and fourth irradiation areas are shielded, and areas other than the second irradiation area are not irradiated.

Once the irradiation platform has passed through the irradiation chamber 5b and has been transferred to the second main chamber part 8.

Switch the irradiation area of the wafer again. In this way, the above-mentioned operation is repeated, and when the third and fourth irradiation areas of the wafer are also irradiated and the entire wafer is irradiated, the irradiation stage is transferred from the second main chamber 77 section 8 to the first chamber section 7. move. The wafer 12 with the circuit pattern transferred onto the entire surface of the wafer is transferred to the chamber 3 by an unloading device.
The wafers are stored one by one in the wafer unload cassette 14 inside. If it is necessary to replace the mask 16, the mask moving device can be used to return the mask to the cassette 15 and take out another mask 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 stands.

As shown in FIG. 4, wafer load cassette storage chambers 2 are provided on both sides of the first main chamber portion
and a wafer unload cassette storage chamber 3 are connected to each other. Inside the loading chamber 2,
A table 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, and this table 30 is supported by a lifting device 31. Cassette 1 supported on stand 30
3 is lowered vertically downward by the lifting device 31 each time one wafer is carried into the first main chamber portion 7.

The loading of the wafer from the cassette 13 into the first main chamber section 7 is performed by a wafer loading device 32 of the invention shown in FIG.

The carry-in device 32 receives the wafers 1 collected by the button inside the cassette 13.
2 is placed on the upper surface and pulled out from the cassette 13, a sliding part 35 for sliding this stage 33 in the horizontal direction along a guide 34, and a drive device 40 for driving the sliding part 35. ing. The wafer 12 placed on the table 33 is moved to above the wafer pushing device 36 by operating the drive device 40 and moving the sliding part 35 along the guide 34. As shown in FIG. 8, a stepped portion 41 is formed that still contacts a portion of the periphery of the wafer 12. The wafer 12 housed in the cassette 13 is taken out from the cassette 13 in such a way that it is hooked by the stepped portion 41 .

Here, the drive device 40 will be explained. A capstan 43 is attached to the shaft end of a drive motor, for example a DC motor 42. A steel wire 45 is stretched in an annular manner between the capstan 43 and the pulley 44. wire 4
5 is applied with the required tension by a tensioner 46. The tensioner 46 functions to absorb the expansion and contraction of the wire 45. The wire 45 and the sliding portion 35 are connected via a wire grip 47 with a necessary M vibration force.

The drive motor 42 is operated to rotate the capstan 43, and the steel wire 45 wound around the capstan 43 is rotated in a block. This movement of the steel wire 45 is transmitted to the sliding portion 35 via the wire grip 47, and moves in a direction determined by the rotational direction of the drive motor 42. The position of the sliding part 35 is detected by sensors 48 and 49, and when the sliding part 35 moves by a required stroke, it is stopped by a signal obtained from the position sensors 48 and 49. The positions of the position sensors 48 and 49 are determined by the size of the wafer to be handled.

The drive motor 42 may be installed inside the vacuum chamber, or it may be installed outside the vacuum chamber using a suitable vacuum seal.

The stroke that the sliding part 35 should move is determined by the position sensor 48.
．． However, the same effect can be obtained by installing a position sensor at an arbitrary position, using that position as a reference point for the sliding portion 35, and rotating the capstan 43 by a desired stroke. In this case, an encoder capable of transmitting an angle signal to the capstan shaft or the motor shaft connected thereto may be used. Furthermore, if a stepping motor is used as the motor, the same effect can be obtained without an encoder. The required stroke can also be obtained by operating the capstan shaft using a cam.

The shape of the stepped portion 41 of the table 33 is preferably an arc shape that contacts the largest wafer among the wafers to be handled, and the length between both ends of one arc is equal to the length of the orientation flat part of the largest wafer to be handled. Let's make it bigger. Further, the thickness of the stand 33 is set so that it can fit into the gap between the wafers held in the wafer cassette.

The lifting device 36 has a rotatable wafer bearing surface 37 and an orifice 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 desired direction.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the X-ray transfer device, and FIG. 2 is a view taken along line 1-1 in FIG. Figure 3 is a view along line ■-■ in Figure 1, Figure 4 is a view along line i-4 in Figure 1, Figure 5 is a plan view of the mask, and Figure 6 is the mask and wafer. 7 is a schematic diagram of the wafer loading device of the present invention, FIG. 8 is a diagram showing the IV-IV line of FIG. 7, and FIG. 9 is a diagram showing the intensity and energy of X-rays. FIG. 12... Wafer 33... Stand 34... Guide 4
1...Stepped portion 42...Motor 43...Capstan 44...Pulley 45...
Wire 46...Tensioner Applicant: Canon Co., Ltd., Figure 5, Figure 4, Turn '7'

Claims (2)

[Claims] (1) A table configured to place a wafer on a surface. a sliding part connected to the base; A guide member for guiding the sliding part, and a driving means for moving the sliding part along the guide member. A ueno conveyance device characterized by having the following. (2) The wafer conveying device according to claim 1, wherein the stand is formed with a stepped portion that comes into contact with the periphery of the wafer.