GB2056758A - Device for air locking objects in corpuscular irradiation devices - Google Patents

Abstract

In the device the objects are mounted on object mounts (6) for transport by a transport mechanism (9) between a cross-slide (2) seated in the housing of the evacuated object chamber (1) of the device and at least one evacuation air-locking chamber being vacuum tightly connected to the object chamber, wherein the air- locking chamber (10), simultaneously charged with a plurality of object mounts, is in the form either of a double air-lock (10) or of a magazine air-lock (Fig. 5, not shown) with a central portion, and at least one evacuation ante-chamber (21, 22,) is provided lockable by a gate (30, 31,) towards outside, a lifting mechanism (36) is seated for receiving the object mount and is provided with sealing means (27) for sealing the central portion against the aerated ante- chamber (21 or 22) and is vertically displaceable by a lifting rod (39) extending to the outside; the transport mechanism comprises a changer (13) seated in a housing of said device and being horizontally and vertically movable, and three ball-pins (5, 18, 41) are provided as seatings for the object mount on the cross-slide, on the changer and on the lifting mechanism respectively, staggered relative to each other by 120 DEG , and being adapted to three V-slots (such as 8) staggered relative to each other by 120 DEG and being radially arranged on the mounting faces of the object mount, the air-locking chamber alternatively being a magazine double air- lock comprising at each side of said central chamber a horizontally arranged ante-chamber (Fig. 6, not shown) capable of being air-tightly sealed to said central part for receiving one magazine each, including a horizontally moveable slide and said lifting mechanism is for vertical movement. <IMAGE>

Description

SPECIFICATION Device for air locking objects in corpuscular irradiation devices The invention relates to a device for air locking objects in corpuscular irradiation devices, where the objects are positioned in object mounts and are transported by a cross-slide seated in the housing of the evacuated object chamber of the corpuscular irradiation device into and back from at least one evacuated air locking chamber air tightly connected to said object chamber.

Such air locking devices are part of the scanning electron devices and of electron irradiation devices for inspection and processing, respectively, of semiconductor discs, masks and mask substrates. Highest requirements are involved as concerns reliability, stability, and reproducibility of the respective components.

When, for example, silicon discs are directly worked on, several operation steps are alternatingly performed within and outside of the corpuscular irradiation device, at an approximately 100% alignment accuracy and reproducibility, respectively, of < 0.1 ym between object position and beam that was to be maintained during the following operation steps.

At the same time, the high expenditures in technology necessitate a minimizing of the time involved in air locking and positioning as well as in all other operational steps to obtain a high output.

In scanning electron microscopes and electron probe devices it is common use to open the entire object chamber for inserting largesize objects manually, and subsequently to position them to details of interest under simuitaneous observation of the electron optical or light optical image.

In the mass production of metal layers evaporated onto glass or onto ceramics by means of an electron beam there are multistage input and output air locking devices where the objects themselves are arranged in close sequence on a rail function as sealing means.

In the working position the positioning operation is comparatively coarse, for each object is only worked once, as disclosed in the GDR WP 86833.

The DT-OS 2 403 349 discloses a device for irradiating individual objects in a magazine supply container. A slide serves to transport the magazine in charging direction.

A swivel arm with a grab takes a selected object out of the magazine, swings it into irradiation position and, after the irradiation has been carried out, is returned to the magazine.

Concerning the air-locking of photomaterial in electron-optical devices there is also a great number of solutions. Neither does this case require a precision positioning, since the material is only one time exposed to the strongly magnified picture.

The DT-OS 2506863, for example, discloses a corpuscular irradiation device with a supply container for the photo material. Said container can be evacuated, detached from the housing of the device, and permits transportation.

The DT-OS 2 506 806 discloses a corpuscular irradiation device with two air locking chambers attached to the housing which are alternatingly operated.

In the Journal "Jenaer Rundschau" 4/1977 an electron beam control, measuring and exposure device describes a practical solution of the air-locking and positioning procedure.

An air locking chamber is vacuum tightly attached to an object chamber, both chambers can be separated by an interior air-locking gate.

After removing the exterior gate of the airlock the maga2ine vvith the object mount is attached.

After evacuating the air-lock and the magazine the interior gate is opened.

A long feed rod is air tightly seated in the magazine. The object mount is manually moved by means of said rod into the object chamber and into the cross-slide, which is automatically brought into the correct position beforehand. The object mount moves this path on rolls.

In the end-position range the cross-slide rolls move in grooves and the object mount moves on lugs. Two balls are provided as stops in the feed directions, to which an edge and a plane face of the object mount abut, in the course of which friction forces have to be overcome. The end position obtained is maintained by spring forces. The required reproducible position depends on the friction coefficient, higher spring force does not yield a higher accuracy.

All previously known devices position x and y by means of laser length measuring systems.

Reflectors or prisms are provided on the cross-slide. The object exposed to the corpuscular radiation is mounted on an object mount, in which it is transported to air-locking.

The coupling pieces are in the partial procedures differently stressed, which leads to differences between the position indicated and the actual position of the object.

In the event of writing without the aid of markings, of measuring considerable distances, and in real production it is not feasible to correct over and over again the electron beam at given markings in each field as in the case of precision positioning as is common in laboratory tests so that none of the known plants has obtained an output comparable to that in the light optical photolighography.

It is an object of the present invention to obviate the above disadvantages.

It is a further object of the invention to ensure the highest reproducibility of the position of the object relative to the cross-slide, and, in addition thereto, to minimize the time required for the entire object exchange including the steps of evacuating, degassing and tempering.

The solution of the present invention can be employed with advantage in serial production of objects- of identical geometry. The invention permits to render the position of the object mount independent of the frictional coefticients and other interferring mechanical effects, that is, to render it stable and reproducible, even after number of chargings and dischargings.

To this purpose the resulting forces are kept to such so small values that plastic deformations of the coupling means are eliminated.

This, in turn, involves a fully automated transport between the air-lock and the cross-slide.

In the following the features of the invention are disclosed.

The position of the object mount on the cross-slide is defined statically by six degrees of freedom in that three ball-pins are provided at the cross-slide, each being staggered by about 120 , fitting into three prismatic V-slots in the object mount.

In order to utilize the largest base possible a plurality of ball-pin circles permit the use of the largest ball pin circle for seating in the event of object mounts of different sizes. The ball-pins are preferably centrally related to the center of gravity of the object mount, only the weight of the object mount being the counter pressure force.

Such a seating satisfies the Maxwell condition of equal forces at the six points of.contact.

Advantageously, the ball-pins and the slots are made of different materials; agate and brass being selected to prevent cold welding.

It is not necessary to temper the slots when the object mount is used always for the same cross-slide, since an eventually deformed calotte is filled by the ball-pins. To increase the horizontal seating precision by reducing the vertical one the slots have an opening angle of 60 instead of 90'.

To improve the seating precision in the airlock and on the changer, where greater lateral and vertical forces may occur, each three ballpins are advantageously seated upon a different arc of circle upon the cross-slide.

The object air-lock is attached to the object chamber, or is integral with the object chamber. Both chambers are connected with each other through an opening to permit the passage of the changer and the object mount.

The air-lock consists of an intermediate part of the upper and lower ante-chamber.

In the intermediate part a disc is moved either into the upper or into the lower part and seals by its respective end positions the upper or lower chamber.

A seating for the object mounts is provided below and above the disc, which is similar to the seating upon the cross-slide.

Advantageously, the disc is moved by a rod which acts upon the object mount via the lower seating.

The connecting rod extends to the outside through a packing washer, or another vacuum sealing, or a frictionless sealing, the driving means are electrical ones, hydraulic ones or pneumatic ones.

Each ante-chamber has a gate to the outside through which the object mount can be inserted or removed manually.

When the disc seals the upper ante-chamber the changer passes the object mount below the disc to the cross-slide for processing, whilst the processed object mount can be exchanged after ventilation and opening of the gate, and the evacuation of the antechamber follows after closing the gate.

After the object has been worked the changer returns the object-mount.

After swinging back the unloaded changer to the object chamber a similar working cycle follows exchanging the object mount in the lower ante-chamber.

A fully automated operation over a long time, the charging of a plurality of objects at the same time or the insertion of full magazines, has to be feasible. With this embodiment the cross-slide, changer and central part at the air-lock remain the same.

The disc of the air-lock has in the upper part a plurality of storages for object mounts or means for inserting a magazine. The upper ante-chamber is provided with a respective bulge.

Instead of the lower ante-chamber a bucket is attached which receives the lowered disc, when the upper object mounts are mounted upon the cross-slide.

A charging of the object mount at will is feasible after a corresponding disc position is obtained.

This modification permits to carry out evacuation of the object mount to be charged either during the working time of an object mount or when the working of the preceding object of a charge takes place after the exchange in the upper ante-chamber. A seating place has to be kept free for the object mount which is in stand-by position upon the crossslide, while a new charging is performed.

A third modification provides two separate air-locks of conventional construction with a radially pressure-fitted interior gate.

A symmetrically constructed changeris arranged between the air-locks and alternatingly takes the object mounts out of the air locks for charging the cross-slide and returns them into the same air-lock.

In a further advantageous embodiment a magazine double-air-lock is provided including two ante-chambers which are horizontally and air-tightly attached to the central part. Each ante-chamber is capable of receiving a magazine. A horizontally moveable cross-slide is arranged in the air-lock. Preferably at right angles to the object-mount displacement direction a lift is arranged in the central part of the air-lock, said lift passes through an opening in the slide base to the seatings of the magazine.

At the upper end portion of the lift a disc is provided for receiving the magazine arranged in the central part.

Advantageously the ante-chambers are connected to a temper-system thus eliminating an otherwise required tempering chamber.

In order that the invention may be more readily understood reference is made to the accompanying drawings which illustrate diagrammatically and by way of example five embodiments thereof and wherein: Figure 1 to 7 show schematical views of the inventional air-locking device.

In an object chamber 1 (Fig. 1) a cross-slide 2 is seated on balls 3 upon the base of a housing 4. The cross-slide 2 is provided with three ball-pins 5 on an arc of circle staggered by 120 relative to each other, upon which the object mount 6 is precisely seated by means of three prismatic grooves 8. An object 7 is mounted upon the mount 6. A change 9 transports the object mount from a double airlock 10 (Fig. 3) to the object chamber 1 through an opening 11. A seating 1 2 is fast with the housing 4 and guides an axle 1 3 secured to a lever 1 4.

A flange 1 5 is provided on the seating 1 2 to which a pivot arm 1 6 (Fig. 2) is hinged.

A lever 1 4 and the pivot arm 1 6 are rotatably connected to a beam 1 7.

The lever 14, the flange 15, the pivot arm 1 6 and the beam 1 7 form a square joint for substantially linearly controlling the transport of an object mount in the range of the double air-lock 10 (Fig. 3) and the opening 11.

The beam 1 7 supports three ball-pins 1 8 for receiving the object mount when the axle 1 3 is lifted until the arrest 1 9 abuts against the seating 1 2.

The double air-lock 10 is connected to the object chamber 1 through a central part 20, to which a lower ante-chamber 21 and an upper ante-chamber 22 are attached.

Flange faces 23 and 24 extending into the interior of the ante-chambers 21 and 22 from the arrest faces for a disc 25 which in the position represented air-tightly seals the antechamber 21 by the sealing washer 26.

The washer 27 seals the ante-chamber 22 in the upper position of the disc 25.

The openings 28 and 29 which serve for insertion of or to remove the object mount are air-tightly sealed by the gates 30 and 31 with the washers 32 and 33.

The ante-chambers 21 and 22 are pressure regulated via the vacuum openings 34 and 35.

The disc 25 is a part of the lifting mechanism 36 and is connected with a mount 37 via pins 38. The lifting movement is effected via a rod 39 seated in the ante-chamber 21.

The disc 25 and the mount 37 are each provided with three ball-pins 40 and 41 for receiving the object mounts 6 and 42, by means of the slots 8 and 43. The arcs of circle 44 and 45 indicate the path of the joints of the beam 1 7 from the initial position 46 via the exchange position 47 up to the airlocking position 48.

Instead of the double air-lock 10 described the installation of a magazine air-lock 49 is feasible (Fig. 5).

The central part 50 of the magazine air-lock corresponds to the central part 20 of the double air-lock 1 0.

An ante-chamber 51 is fitted thereunto.

Flange faces 52 extending to the interior form the abutment faces for a disc 53.

A rod 55 effecting the lift movement is seated in a bucket 54. Intermediate platforms 56 are secured to the disc 53 with spacer pins 57 each carrying three ball-pins 58 for receiving the object mount 59.

The chamber 60 serves to insert or to remove the object mount 59 and is sealed by the gate 61 with the sealing washer 62.

Instead of the rigidly installed intermediate platforms 56, a magazine 63 (Fig. 6) loaded with object mounts can be introduced through the opening and placed upon the disc 53.

A magazine double air-lock according to Fig. 7 comprises a central chamber 64 which is air-tightly connected to an object chamber 1, and two ante-chambers 65 and 66 laterally attached to said central chamber 64.

The ante-chambers 65 and 66 can be sealed against the central chamber 64 by respective seals. A slide 68 is seated for horizontal movement in said chambers 64, 65, 66.

One of the ante-chambers 65, 66 is vacuum connected to the central chamber 64, at the same time sealing means 69, 70 sealing.

the connected chambers to the respective other one. The operation is as described above in respect to the double-air-lock.

The slide 68 also functions as a mount for two magazines 71, 72 with reception guides 73, 74 for the magazines at both sides of a slide disc 75.

Each magazine carries a number of object mounts 59 stacked at spaced relation, as already disclosed in connection with Fig. 5.

The seating for each magazine on the slide is such that it can be freely lifted off and returned to the slide. A disc 78 or a vertically moveable lift 79 can pass an opening 76 and 77, respectively, of the slide base, and lift the magazine into a proper height and return it.

Hereinafter one operation cycle of the airlocking system of the present invention is described.

The interaction between the electron beam and the object 7 is finalised; the pre-evacu ated ante-chamber 21 is charged with the next object mounted on the object mount 42.

The beam 1 7 of the changer 9 in the standby position is in the lowered position. The cross-slide 2 is moved into the position provided for an object change.

The changer 9 is operated by rotation of the axle 1 3 into the exchange position 47 and is located centrally below the object mount 6.

The changer 9 is lifted by motion of the axle 1 3 until stopped at the arrest 1 9 of the seating 1 2 and thus the object mount is lifted upon the ball-pins 1 8 of the beam 1 7 and taken off from the ball-pins 5 of the crossslide 2. In this upper position the changer 9 is operated until arrived at the air-locking position 48, The object mount 6 rotates about 90 in the course thereof.

When lowering the changer 9 the object mount 6 comes to rest upon the ball-pins 41 of the disc 25 and the beam 1 7 further lowers and, in its lowest position, is returned into the object chamber 1 to open the path for the lifting mechanism 36.

The vacuum valve 34 is closed and the lifting mechanism 36 is brought into the upper position by movement of the rod 39, thus closing the ante-chamber 22 by joining the disc 25 with the sealing 27.

The ante-chamber 22 is aerated via the vacuum connection 35, the gate 31 is opened, the object mount 6 removed and a prepared new object mount inserted. After closing the gate 31 and turning off the ventilation system, the pre-evacuation starts via the vacuum connection 35. During the time of exchanging the object mount the changer 9 is move into the air-locking position 48 and the beam 1 7 is placed under the object mount 42 which carries an object which has been evacuated, degassed and tempered while the object 7 has been worked.

The changer 9 is lifted and the object mount 42, received by the ball-pins 1 8 of the beam 17, is brought into the change position 47 by rotating the axle 1 3. By lowering the changer 9 the object mount 42 is placed upon the ball-pins 5 of the cross-slide 2. The changer 9 is moved into the stand-by-position 46.

The time of the interaction between the electron beam and the object upon the object mount 42 is used for a further pre-evacuation, degassing and tempering of a new object in the ante-chamber.

The operation cycle of the next object change runs in analogy thereto however with the ante-chambers exchanged.

The operation of the magazine double airlock as described in connection with Fig. 7 is as follows:- The slide 68 is moved into the left-side endposition and hence the ante-chamber 65 is air-tightly sealed towards the central chamber 64.

The ante-chamber 65 is aerated, the gate opened and the first magazine inserted into the slide, then the gate is closed. After tempering and subsequent evacuation via the connection 82 the slide is moved onto the right arrest thus air-tightly closing the antechamber 66.

A second magazine is inserted in the right reception rails, while the first magazine is worked on in the operating chamber after having been lifted into the right operation height. The first magazine is returned to the lower arrest 81 and then into the left endposition where a new first magazine can be charged. In the meantime the-second magazine has been subject to the same operation steps as the first one and is now in the operating chamber. Thus the first operation cycle is closed.

Claims (11)

1. ~ Device for air-locking objects in corpuscular irradiation devices, the objects being mounted on object mounts for transport by a transport mechanism between a cross-slide seated in the housing of the evacuated object chamber of said device and at least one evacuation air-locking chamber being vacuum tightly connected to the object chamber, wherein the air-locking chamber, simultaneously charged with a plurality of object mounts, is in the form either of a double airlock or of a magazine air-lock with a central portion, and at least one evacuation antechamber is provided lockable by a gate towards outside, a lifting mechanism is seated for receiving the object mount and is provided with sealing means for sealing the central portion against the aerated ante-chamber and is vertically displaceable by a lifting rod extending to the outside; the transport mechanism comprises a changer seated in a housing of said device and being horizontally and vertically movable, and three ball-pins are provided as seating for the object mount on the.cross-slide, on the changer and on the lifting mechanism, staggered relative to each other by 120 , and being adapted to three Vslots staggered relative to each other by 120 and being radially arranged on the mounting faces of the object mount, or the air-locking chamber is a magazine double air-lock comprising at each side of said central chamber one horizontally arranged ante-chamber, each capable of being air-tightly sealed to said central part for receiving one magazine each, including a horizontally moveable slide and said lifting mechanism is for vertical movement.

2. Device as claimed in claim 1, wherein the ball-pins of the cross-slide, of the changer and of the lifting mechanism are on different arcs of a circle.

3. Device as claimed in claim 1 or 2, wherein a plurality of ball-pin circles are provided on the cross-slide.

4. Device as claimed in claim 1, 2 or 3, wherein the V-slots of the object mount have an opening angle of 60 .

5. Device according to any of the preceding claims 1 to 4, wherein the ball-pins and the V-slots are made of different material, the ball-pins being made of the harder material.

6. Device as claimed in any of the preceding claims, wherein in the event of the air-lock being a double air-lock an upper and a lower evacuation ante-chamber is provided for the central part and the lifting mechanism substantially consists of a carrier with ball-pins secured to a rod and of a disc with ball-pins connected to the carrier via studs, the disc carrying the sealings.

7. Device as claimed in any of preceding claims 1 to 5, wherein in the event of the airlock being a magazine air-lock an evacuation ante-chamber and a bucket for receiving the lowered object mount magazine are attached to the central part.

8. Device as claimed in any of the preceding claims 1 to 5, wherein the central part includes a lifting mechanism which passes openings in the slide base for mounting the magazines, and which is provided with a disc at its upper end portion for receiving the magazine.

9. Device as claimed in any of the preceding claims, wherein the lifting rod is electrically, hydraulically or pneumatically driven.

1 0. Device as claimed in any of the preceding claims, wherein the changer is in the form of a joint square comprising a lever, a flange, an arm and a beam, the beam carrying the ball-pins.

11. Device as claimed in claim 1, wherein two separate air-locks are attached to the object chamber alternatingly charged, and a symmetrical changer is provided between the air-lock chambers.

1 2. A device as claimed in claim 6 and 8, wherein the horizontally arranged ante-chambers are connected to a tempering system.

1 3. A device for air-locking objects in corpuscular irradiation devices substantially as hereinbefore described with reference to Figs.

1 to 4 or to Figs. 5, 6 or 7.