DE10341594A1 - Arrangement for highly precise positioning and measuring of objects placed on an object table, e.g. for use in producing microstructures in semiconductor manufacturing, has an interferometer block and measurement mirrors - Google Patents

Abstract

Arrangement for precise positioning and measuring of objects placed on an object table whereby in a positioning volume beneath the object table (1) is an interferometer block (25) that is made up of two partial blocks whereby each block contains at least an interferometer. Measurement reflectors (20-22) of the interferometer are arranged on the inner surfaces (23, 24) of the object table and the closing plate.

Description

The The invention relates to an arrangement for highly accurate positioning and measuring objects arranged on object tables and in particular for positioning and measuring the position of provided these objects arranged objects. The application of Arrangement is z. B. provided in the production of microstructures Wafers in chip and circuit manufacturing in the microelectronics industry.

Around an object placed on an object or coordinate table Clearly positioning in the room are movements of the table required in six degrees of freedom. It is this three linear Shifts along the Cartesian coordinate axes x, y and z and three rotations about these coordinate axes. The coordinate tables are built so that the the object carrying table can perform all these six movements.

Commonly known coordinate tables are arranged as cross tables with orthogonally arranged guides for movements in the x and y directions, in which positioning drives for the z direction are additionally provided. It is also generally known to use interferometric laser measuring systems for the metrological detection of these movements. Such coordinate tables have measuring reflectors for the interferometric measuring systems on orthogonal sides. The associated interferometers are the measurement reference points from which the measurement is defined. Since the interferometers are outside the range in which the table movement takes place, the Meßbezugspunkte have relatively large spatial distances from each other and from the DUT or from the coordinate table, so that the measurement results depend significantly on mechanical and thermal influences. Positioning and measuring accuracy in Nanome terbereich are therefore hardly or only with great technical effort possible. Corresponding positioning systems are for example off US 5,764,361 . DE 195 05 033 A1 and PCT / US 990/05879.

Also positioning systems on supports with variable lengths in the manner of a hexapod are out DE 199 38 602 A1 and US 5 604 593 in which the movements are detected interferentially with interferometers integrated in the supports.

Out US 5,764,361 PCT / US90 / 05879, DD 296 754 and DD 296 755 multiaxial interferometer measuring systems are known. These references describe compact interferometers for one, two or three axes arranged in an interferometer block. Here three interferometers are required for one axial direction, which serve the position and angle measurement in each case two axes perpendicular to the beam direction axes. For the coordinate directions x, y and z, a measuring reflector is provided in each case. When probing the reflectors with external interferometers, a maximum of three interferometers are required for each axis, which can be implemented in a compact block. However, compact interferometers for more than three axes are not described.

From "APPLIED OPTICS" / Vol. 33, no. 1/1 January 1994, page 32, 1 and the accompanying text, a micro-scanning table is known, which is movable in the three coordinates X, Y and Z. To determine the position of the table, three laser interferometers arranged outside the table are provided. The measuring reflectors associated with the individual coordinates in the form of triple mirrors are mounted on the three mutually perpendicular surfaces of the table.

So the invention is based on the object, an arrangement for highly accurate Positioning and measurement of objects arranged on object tables to create which is compact and largely invariant against environmental influences and with what very accurate measurements and positioning in six Degrees of freedom largely free of mechanical and thermal influences carried out become.

According to the invention this Task with a Positionierensorsystem according to the preamble of Hauptanspruches solved with its characterizing means. In the dependent claims Details and further embodiments are disclosed.

So it is advantageous if the orthogonal to each other surfaces the object table and the object table plate are formed as reflectors, which is the function of measuring reflectors have.

Of the provided in the adjustment volume below the stage Interferometerblock is advantageous from two sub-blocks composed. This is called "adjustment volume" the space in which the object table can be moved.

So it is advantageous if the six interferometers of the interferometer block are arranged so that everyone Part block includes three interferometers.

It is also advantageous if a first sub-block each comprises an interferometer for measuring the positions in the X and Y directions and for measuring the rotation about the Z coordinate. The same is true In part, if a second sub-block each comprises an interferometer for measuring the position in the Z-coordinate and for measuring the rotations about the X and the Y-coordinate.

Around the influence of external conditions, in particular the temperature influence on the measurements and positioning To be largely eliminated, the beam paths are advantageous, in particular the reference beam paths, the six interferometers largely or completely within are arranged of the interferometer block. This applies to all beam paths with Exception to the measuring reflectors out Meßstrahlengänge.

Around a stable and compact design of the interferometer block too reach, are the two sub-blocks by wringing or kitten are connected together at a parting plane to form a unit.

In In the sense of a compact unit, it is also advantageous if a each of the two sub-blocks radiating elements, Interferometers and reflectors in the form of reference reflectors includes.

It is also advantageous that at least a beam splitter cube Also has at least one polarization optically effective splitter surface.

to radioguide Within the interferometer block, the radiation-guiding elements are advantageous as a beam splitter cube and / or 90 ° beam deflector (Reflectors) formed. As a beam deflector and roof prisms can be provided be.

From Advantage and in terms of an effective production of the interferometer cube is it, if the radiating Elements and / or the reference reflectors at the sub-blocks sprinkled or are cemented.

The Invention will be explained in more detail below using an exemplary embodiment.

In show the drawing

1 in a simplified, perspective view of a stage with guides, actuators and interferometer block,

2 the further possible arrangement of the actuators,

3 the connections of the actuators with the stage,

4 an interferometer block with incoming and outgoing beams and reflectors associated with the coordinates,

5 the interferometer block in a different position,

6a and 6b the beam path in the one sub-block of the interferometer block and

7a and 7b the beam path in the other sub-block of the interferometer block.

In 1 is a stage 1 shown in perspective, on which the object (not shown), for example, a wafer, is arranged. The stage 1 is guided in three coordinates X, Y and Z and can be pivoted about these coordinate axes X, Y and Z. On a machine bed 2 are guide rails 3 and 4 provided on which carriage 5 . 6 and 7 slidably mounted in the X direction (a fourth carriage is in 1 not visible) through a first frame 8th are firmly connected. dare 5 . 6 and 7 as well as the frame 8th together form the X-table, on which guide rails 9 and 10 are arranged on which by a second frame 11 rigidly connected cars 12 . 13 and 14 (the fourth car is in 1 not visible) are stored. dare 12 . 13 and 14 as well as the frame 1 1 form the Y-table on which the stage 1 adjustable in the Z direction and is arranged rotatably about the coordinate axis Z. The storage of the car on the guides is advantageously realized by known recirculating ball elements. For highly precise adjustment of the stage 1 in Z-direction are actuators 15 . 16 and 17 provided between the frame 11 and the stage 1 are arranged. A rotation of the Objektti cal 1 around the Z-axis is through an actuator 18 realized. As actuators advantageously suitable piezo drives are provided. The actuators 15 . 16 . 17 and 18 are stuck with the frame 11 connected.

The stage 1 is designed as a downwardly open, rigid component. Below his, the bearing surface for the object forming end plate 19 are three as Meßreflektoren 20 . 21 and 22 Serving, level mirror fixed to orthogonal receiving surfaces 23 . 24 of the stage 1 fixed, with one measuring reflector 22 (in 1 dashed lines), which is provided for measurements in the Z direction, the lower surface of the end plate 19 forms.

In the below open space of the object table 1 is an interferometer block 25 the interferometric measuring system, preferably centrally, fixed to the machine bed 2 arranged.

While in 1 the actuators 15 . 16 . 17 and 18 at the four corners of the frame 11 are arranged, ie 90 ° to each other, shows 2 the arrangement of the actuators 15 . 16 . 17 and 18 offset by 60 ° to each other. With the actuators 15 . 16 and 17 associated arrows should be realized in the Z-direction and with the actuator to be realized 18 associated arrow rotation around the Z coordinate axis are marked.

3 shows the moving links on the frame 11 arranged actuators 15 to 18 with the stage 1 , These compounds are designed so that the smallest position changes of the moving parts of the actuators without generating mechanical stresses on the measuring or object table 1 be transmitted. This is done, for example, in such a way that the actuator 15 as a fulcrum through a connection by means of a cone in cones 27 . 28 resting ball 28 with the stage 1 connected is. The edition of the table 1 on the actuators 16 . 17 gets through one on levels 29 . 30 resting ball 31 realized. The connection between the stage 1 and the actuator realizing the rotation about the Z coordinate axis 18 For example, by a membrane 32 carried out, which is designed so that it transmits the pivotal movement about the Z-axis rigid, ie without slippage, but height movements of the movable part of the actuators 15 to 17 resiliently compensates in the Z direction.

The 4 and 5 show the interferometer block 25 in a perspective view in different views. The interferometer block 25 consists of two blocks assembled by kitten or wringing 33 and 34 where each of these sub-blocks 33 and 34 is constructed so that it can take over the function of three interferometers. The connecting surface, preferably a cemented surface, is with 35 in the relevant figures. This interface 35 between the sub-blocks 33 . 34 is designed as a beam splitter surface with at least partially polarizing properties. At the subblock 34 are ray-guiding, optical elements 36 to 41 arranged or assigned to this, which as radiation-deflecting single prisms 38 . 41 and / or as known per se, composed of individual prisms beam splitter and / or deflection prisms 36 . 37 . 39 and 40 are formed. Through the radiation-guiding elements 36 to 41 is emitted by the laser light source (not shown), in the beam-guiding optical element 36 entering laser light beam E divided into partial light bundles E1 to E6, which in the sub-block 34 irradiated and fed to the individual interferometers. The deflecting prisms are usually 90 ° Umm prisms.

In the 4 and 5 are also the three measuring reflectors 20 . 21 and 22 shown, wherein the measuring reflector 20 the Y-coordinate, the measuring reflector 21 the X-coordinate and the measuring reflector 22 is assigned to the Z coordinate. On these Meßreflektoren 20 . 21 and 22 meet the measuring beams M1 to M12 ( 4 and 5 ) of the six, in the interferometer block 25 realized interferometer and are at these Meßreflektoren 20 . 21 . 22 into the interferometer block 25 reflected back to the interference points of the interferometer inside the block 25 to interfere with the corresponding, belonging to the individual interferometers reference beams. The reference beam paths are in the 4 and 5 not shown, as they are within the corresponding sub-blocks 33 and 34 run. The leaving the interference points, and from the sub-blocks 33 and 34 of the interferometer block 25 emerging beam A1 to A6 are in a conventional manner, advantageously by optical fibers, photoreceptors and an evaluation unit (not shown) supplied. From the signals supplied by the photoreceptors in the evaluation unit, the position and the spatial position of the object table 1 determined. The detailed course of the beam paths in the interferometer block 25 will continue under in connection with the 6a . 6b . 7a and 7b explained.

As already stated, each of the two sub-blocks comprises 33 . 34 three interferometers. So includes the subblock 34 the three for the measurements of the positions of the Objektti cal 1 in the X and Y coordinates and for the rotation or tilting of the table 1 around the Z-coordinate interferometer provided. For the measurements of positions in the X-coordinate, the incoming partial light bundle E2 and the outgoing beam A2 are provided. For measurements in the Y-coordinate, the incoming partial light bundles E1 and E3 and the interference block 25 leaving beam A1 and A3 used. A rotation or tilting of the stage 1 The Z coordinate axis can be determined in the evaluation unit from the two determined positions in the direction of the Y coordinate and from the distance of the beam bundles A1 and A3.

The subblock 33 comprises, as already stated, also three interferometers with interference points at which the Z-coordinate associated measuring reflector 22 reflected measuring beam M7 to M12 and the inside of the interferometer block 25 extending reference beam bundles interfere. These interferometers are the incoming partial beams E4 to E6 and the interference block 25 leaving beam A4 assigned to A6. The reflectors associated with the interferometers, preferably designed as triple prisms 42 to 49 which in the 4 and 5 are visible outside on the sub-blocks 33 and 34 arranged. These reflectors 42 to 50 (Reflector 50 is not visible), which are designed as triple prisms known per se, are advantageous to the sub-blocks 33 . 34 cemented. On the, the measuring reflectors 20 . 21 . 22 facing surfaces of the sub-blocks 33 . 34 are also arranged at the exit points of the measuring beam M1 to M12 polarization-optical effective λ / 4 plates, which change the position of the polarization plane of the continuous beam.

In the view after 4 visible, are on the measuring reflector 22 facing surface 51 of the subblock 33 at the exit points of the measuring beam M7 to M12 polarization optically effective, the plane of polarization by 90 ° rotating λ / 4 plates 53 . 54 . 55 arranged.

The inside of the interferometer block 25 extending reference beam paths of each individual, said interferometer are rigid in the interferometer block 25 , The reference beam paths are the path between the corresponding intersection points of the reference beam with the corresponding associated polarization-dividing surface of the respective associated interferometer. The rigid in the interferometer block 25 guided reference beam paths offer the great advantage that they are invariant to external, especially temperature-related influences. It only needs the temperature influence on the interferometer block 25 get noticed. By keeping the temperature constant and using, for example, quartz glass for the interferometer block 25 These temperature-induced errors can be largely eliminated or avoided.

The 6a and 6b show the configuration of the sub-block 34 of the interferometer block 25 in various views, which includes beam paths of three interferometers, which serve the measurement along the X and Y coordinates and the measurement of the rotation about the Z coordinate. The beam paths of the individual interferometers are briefly explained below.

In the beam path of the measuring in the X direction interferometer is in the sub-block 34 entering partial light bundle E2 to one inside the Interferometerblokkes 25 provided polarization splitter layer 52 guided and split at this into two partial beams T21 and T22, wherein the polarization planes of these partial beams T21 and T22 are orthogonal to each other. The polarization splitter layer 52 passing partial beams T21 is the reference beam in the beam path of the measuring in the X direction interferometer and is at reflector 45 ' thrown back in parallel. That at the polarization splitter layer 52 reflected partial beams T22 is the measuring beam of the measuring in the X direction interferometer. This partial beam T22 is via one on the sub-block 34 arranged λ / 4 plate 56 to the measuring reflector 21 steered and is reflected there in itself. By re-passing through this partial beam T22 through the λ / 4 plate 56 becomes the plane of polarization of the partial beam 22 rotated by 90 °, so that this the polarization splitter layer 52 pass and to the reflector 45 , can get. From the reflector 45 reflected, the partial beam passes 22 through the polarization splitter layer 52 again to the measuring reflector 21 , is reflected there and on the λ / 4 plate 56 becomes the plane of polarization of the partial beam 22 rotated again by 90 °. At the polarization splitter layer 52 which also forms the interference plane of the relevant interferometer, the partial beam T22 is reflected and interferes with that at the reflector 45 reflected and the polarization splitter layer 52 passing partial beams T21 of the interferometer. The beam A2 leaves after interference at the layer 52 the interferometer block 25 and is supplied to a photoreceiver (not shown). The X-measured values are then determined in the evaluation unit from the photoreceiver signals.

For the measurement in the direction of the Y-coordinate and for the measurement of the rotation about the Z-coordinate are in the sub-block 34 of the interferometer block 25 integrated two more interferometers. Here the two entering partial light bundles E1 and E3 are used.

Thus, one of these two interferometer beam paths according to 6a and 6b as follows:
That in the subblock 34 of the interferometer block 25 entering partial light bundle E1 is at the polarization splitter layer 52 in a partial beam T11 (reference beam) and a, the measuring beam of the interferometer forming a partial beam T12 split. The partial beam T11 is at the reflector 50 and at the polarization splitter layer 52 reflected. The partial beam T12 passes through the polarization splitter layer 52 and passes through a λ / 4 plate 57 in the direction of the measuring reflector 20 , is reflected there, again passes through the λ / 4-plate 57 , becomes at the polarization splitter layer 52 reflected and to the reflector 46 guided and reflected there. This partial beam T12 is then applied to the polarization splitter layer 52 again towards the measuring reflector 20 deflected and interferes with reflection on the measuring reflector 20 and after passing the λ / 4 plate again 57 in the interference plane (polarization splitter layer 52 ) with the partial beam T11 and leaves as beam A1 the beam splitter block 25 ,

The other of these two, the Y coordinate associated interferometer beam paths is like follows:
The partial light bundle E3 is after entry into the sub-block 34 at the polarization splitter layer 52 split into a partial beam T31 (reference beam) and into a partial beam T32 (measuring beam). The partial beam T31 is at the reflector 49 and at the polarization splitter layer 52 reflected. The polarization splitter layer 52 passing partial beams T32 passes through a λ / 4-plate 58 in the direction of the measuring reflector 20 , is reflected in it and again passes through the λ / 4-plate 58 is at the polarization splitter layer 52 towards the reflector 44 deflected towards the reflector and 44 reflected. The partial beam T32 is then applied to the polarization splitter layer 52 again in the direction of the measuring reflector 20 deflected and interferes after reflection at the reflector 20 and after passing the λ / 4 plate 58 in the plane of the polarization splitter layer 52 , which represents the interference plane of this interferometer, with the partial beam T31 and leaves as beam A3 the interferometer block 25 ,

The the interferometer block 25 constituting beams A1 and A3 are supplied to photoreceivers, not shown. From the photoreceiver signals, the Y measurement values and measured values for the rotation about the Z coordinate are determined in the evaluation unit.

The incoming partial beams E1 to E3 are opposite to the partial block 34 leaving sub-beams A1 to A3 laterally offset, which is off 6b can be seen.

In the 7a and 7b become the ray trajectories of the subblock 33 of the interferometer block 25 associated interferometer, which are responsible for the measurements in the direction of the Z-coordinate and for measuring the rotations about the X and the Y-coordinate. The subblock 33 includes the polarization splitter layers 59 and 60 , in which also the interference levels of the interferometer concerned are.

How out 7a This is the sub-block 33 of the interferometer block 25 entering partial light bundles E4 at the polarization splitter layer 60 split into a partial beam T41 and a partial beam T42, wherein the partial beam T41, the reference beam of an interferometer of the block 33 is. The partial beam T41 is at the reflector 43 to the polarization splitter layer 60 offset ( 7b ) thrown back. The polarization splitter layer 60 passing partial beams T42, which is the measuring beam of this interferometer, passes through the λ / 4-plate 55 , is at the measuring reflector 22 reflected and after further passing the λ / 4 plate 55 at the polarization splitter layer 60 to the reflector 48 deflected where the partial beam T42 to the polarization splitter layer 60 is reflected back. At the polarization splitter layer 60 is the partial beam T42 again to the measuring reflector 22 diverted. After reflection at the measuring reflector 22 and pass through the λ / 4 plate 55 the partial beam T42 interferes in the plane of the polarization splitter layer 60 with the partial beam T41 and leaves as beam A4 the interferometer block 25 ,

That in the interferometer block 25 entering, the other interferometer of the sub-block 33 associated partial light bundle E5 is at the polarization splitter layer 60 split into the partial beams T51 and partial beams T52, whose leadership in the block 33 laterally offset to the beam guidance in the first interferometer, wherein reflections of the partial beam T51 and the partial beam T52 to the Re reflectors 42 and 47 done and the λ / 4 plate 53 (not visible in 7a ) is passed several times through the partial beam T52. After interference of the partial beams T51 and T52 in the plane of the polarization splitter layer 60 the beam A5 leaves the interferometer block 25 ,

The entering partial light bundle E6 of the third interferometer of the sub-block 33 is at the polarization splitter layer 59 formed in the partial beams T61 and T62. The partial beam T61 is at the polarization splitter layer 59 to the reflector 48 ( 7a ) and from there to the polarization splitter layer 59 directed back where it is also redirected. The partial beam T62 passes through the polarization splitter layer 59 and the λ / 4 plate 54 measuring reflector 22 and becomes the polarization splitter layer there 59 thrown back. After deflection at the polarization splitter layer 59 and reflection at the reflector 42 ( 7b , in 7a by reflector 43 hidden) and repeated deflection at the polarization splitter layer 59 in the direction of the measuring reflector 22 and reflection on this measuring reflector 22 the partial beam T62 interferes with the partial beam T61 and leaves the interferometer block as the beam A6 25 ,

The ray beam A4 to A6 become photo receivers from whose signals in the evaluation the corresponding readings in the direction of the Z coordinate and for the rotations around the X and to be determined by the Y coordinate.

1

stage

2

machine bed

3, 4

guide rails

5, 6, 7

dare

8th

frame

9 10

guides

1 1

frame

12 13, 14

dare

1 5, 16, 17

actuator

18

actuator

19

end plate

20 21, 22

measuring reflector

23 24

receiving surfaces

25

Interferometerblock

26 27

conical seats

28

Bullet

29 30

level

31

Bullet

32

membrane

33 34

partial block

35

interface

36 to 41

radiating elements

42 until 50

reflectors (50 not visible in the figures)

51

surface

52

Polarization splitting film

53 to 55

λ / 4 plate

56 57, 58

λ / 4 plate

59, 60

Polarization splitting film

A1 to A6

ray beam

E1 to E6

Divided light beam

M1 to M12

measuring beam

T11, T21, T31, T41, T51, T61

Partial beams (reference beams)

T12, T22, T32, T42, T52, T62

Partial beams (measuring beams)

Claims (11)

Arrangement for high-precision positioning and measurement of objects arranged on object tables comprising - an object in a displacement in three coordinates by drives measurably displaceable object table for receiving objects to be positioned, wherein the stage for adjusting in two coordinates X and Y on a cross slide assembly and movement in the third coordinate Z is mounted on highly precise controllable, arranged on the cross slide assembly adjustment, - an interferential laser displacement measuring system for determining the displacement and / or the position of the stage consisting of laser light source, beam guiding elements, interferometers with measuring and reference reflectors and evaluable measuring signals generating radiation receiver, wherein the measuring reflectors for the coordinates X, Y and Z are rigidly arranged on orthogonal surfaces of the stage, - and drive means for moving the stage in the Verstellvolum and its angular displacement with respect to the coordinates X, Y and Z, characterized in that - in the adjustment volume below the object table ( 1 ) one of two joined sub-blocks ( 33 . 34 ) existing, Interferometer comprehensive interferometer block ( 25 ), each sub-block ( 33 . 34 ) comprises at least one interferometer - and that the measuring reflectors ( 20 . 21 . 22 ) of the interferometer within the adjustment volume in the interior of the object table ( 1 ) lying orthogonal to each other surfaces ( 23 . 24 ) of the object table ( 1 ) and the end plate ( 19 ) are arranged. Arrangement according to claim 1, characterized in that the orthogonal surfaces ( 23 . 24 ) of the object table ( 1 ) and the lower surface of the end plate ( 19 ) are formed as reflectors. Arrangement according to claim 1, characterized in that each of the two sub-blocks ( 33 . 34 ) comprises three interferometers. Arrangement according to claim 3, characterized in that a first sub-block ( 34 ) each comprise an interferometer for measuring the positions in the X and Y directions and for measuring the rotation about the Z coordinate. Arrangement according to claim 3, characterized in that a second sub-block ( 33 ) each comprise an interferometer for measuring the position in the Z coordinate and for measuring the rotations about the X and Y coordinates. Arrangement according to one of Claims 1 to 5, characterized in that the reference beam paths of the six interferometers within the interferometer block ( 25 ) are arranged. Arrangement according to one of the preceding claims, characterized in that the two sub-blocks ( 33 . 34 ) are joined together by wringing or kitten at a parting plane. Arrangement according to one of the preceding claims, characterized in that each of the two sub-blocks ( 33 . 34 ) radiative elements ( 36 to 41 ), Interferometers and reflectors ( 42 to 50 ), which at the Teilblökken ( 33 . 34 ) are arranged. Arrangement according to one of the preceding claims, characterized in that the radiation-guiding elements ( 36 to 41 ) Beam splitter cube and / or 90 ° beam deflector (reflectors) include. Arrangement according to claim 9, characterized that at least a beam splitter cube has at least one polarization optically acting splitter surface. Arrangement according to one of the preceding claims, characterized in that the beam-guiding elements ( 36 . 41 ) and / or the reflectors ( 42 to 50 ) are sprinkled or puttied on the sub-blocks.