Method and apparatus for leveling, force compensation and contact sensing wherein semiconductor wafers

Cross-reference to related, pending notifications simultaneously

This application US patent application with the claimed the priority of the preliminary 61/847 serial number, 118, lodged on 17 july 2013, entitled "Beheizung sand Verfahren zur oxide semiconductor wafers lEVELING, bALANCING force in sENSINGcONTACT sand", hereby expressly incorporated by reference in the text content is.

This application is a part of the US patent application serial number with the further treatment 12/761, 044, lodged on 15 april 2010, entitled "wafer Vorrichtung zur cENT RING", hereby expressly incorporated by reference in the text content is.

The present invention relates to a device and a method for a wafer bonding apparatus and method and particularly concerns semiconductor wafer bonding, providing a leveling a jig, a force compensation and a substrate contact sensing.

Background of the invention

Wafer to wafer (w2w) in a wide range of semiconductor processing applications is - ounted for forming semiconductor devices applied. Examples of semiconductor process applications to, where wafer to wafer ounted is applied, include substrate engineering and the production of integrated circuits, and encapsulation of microelectromechanical systems (MEMS devices) packaging and stacking many processed layers of pure microelectronics (3d-and-lntegration). W2w ounted comprises orienting of two or more wafers areas, their contacting and forming a strong bonding interface between them. The total processing yield and cost of semiconductor devices and ultimately the cost of electronic products thus prepared, where these components are, to a large extent depend on the quality of the wafer to wafer ounted off. the quality of the wafer of the precise alignment is w2w ounted, maintaining the wafer alignment on the wafer bonding interface and the uniformity and integrity of bond strength to the wafer bonding interface dependent. In particular leveling, planarity, distance and voltage between the wafer surfaces are critical for the bonding quality. Accordingly it is desirable, to provide a reliable, high precision and repeatable positioning of the semiconductor wafer surfaces relative to each other in the wafer bonding apparatus.

The invention provides a device and a method for semiconductor wafer bonding, comprising the leveling a jig, a force compensation and a substrate contact sensing.

In an aspect the invention is a wafer bonding apparatus generally prepared, comprising: a lower jig, an upper jig, a process chamber and three adjusting mechanisms. The lower platen is formed to support therefor, a first wafer, the upper jig adapted, to support a second wafer, and the second wafer is arranged opposite the first wafer. The process chamber is formed between the upper jig and the lower jig. The three adjusting mechanisms are arranged around an upper lid and spaced from each other and are arranged outside the process chamber. Each adjustment mechanism comprises a component for sensing contact with the upper jig, a component for adjusting the biasing force of the upper jig and a component for leveling the upper jig.

Implementations of this aspect of the invention comprise one or more of the following. Each adjustment mechanism further comprises a push-through shaft, the upper lid and a distal end extends through the, which is rigidly attached to an upper surface of the upper jig, and a proximal end, which projects through the upper lid therethrough. By the pusher shaft comprises a material, a thermal expansion coefficient of less than 2 x 10 (temperature coefficient of thermal spring expanding, CTEs)'⁶ C¹ has. The Invar material contains by pusher shaft. The thrust shaft is thermally insulated from the upper jig by thermal break on points.

The component for leveling the upper jig comprises a vernier screw, a vernier screw shaft, a pivot arm and a support plate. The pivot arm is pivotally connected to the support plate and having a first end, which is connected to a distal end of the vernier screw shaft, and a second end, which is connected to the push-through shaft. The vernier screw has a resolution of 1 micrometer and is attached to the proximal end of the vernier screw shaft. Rotational movement of the screw shaft causes linear movement of the vernier vernier screw, and the linear motion of the screw shaft causes linear movement of the thrust shaft by vernier is characterized in that the level of the upper jig and a mounted. The component for leveling the upper jig vernier locking clamp further comprising a screw, the adapted, to lock the position of the vernier screw. Each adjustment mechanism further comprises a sensor for measuring the bias force of the upper clamping device.

The component for sensing contact with the upper jig comprises a contact sensor, and the contact sensor is connected to the proximal end of the push-through shaft. Contacting an underside of the upper jig causes, that the upper chuck and the pusher shaft mounted by the contact sensor a signal move and registered. The component for sensing contact with the upper jig and a biasing spring and a guide further comprising a contact ball bearing interface, and said ball bearing interface adapted, to contact a thrust washer, by surrounding the pusher shaft.

The component for adjusting the biasing force of the upper clamping device includes a screw and a tension spring. The tension spring has a distal end, which is connected to the upper side of the upper jig, and a proximal end, which is connected to the screw. Rotating the screw adjusting the spring tension and thereby the bias force of the upper clamping device. The screw further comprises a plug with a pivoting bearing retainer, and the pivot bearing retainer receives a pivot bearing, which is connected to the proximal end of the tension spring. The component for adjusting the biasing force of the upper clamping device further comprises a circular clamp, the adapted, to limit upward movement of said tension spring.

The device can further comprise a computer application, the adapted, and positions of the three adjustment mechanisms provide images on a display and movement of the upper jig on the component for sensing a contact to control and guide. When a contact with the upper jig is detected, the images on the light adjusting mechanisms, where the contact took place.

The lower jig can be an electrostatic chuck. The electrostatic chuck comprises a ceramic heater with integrated heating wires, a thin dielectric layer on a surface of the ceramic heater and electrical interconnections. The electrical interconnections comprise an electrode block and a wire conductor, surrounded by a ferrule. The electrode block is brazed to a bottom surface of the ceramic heater and is on the top of the ferrule and the Λ

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Electrodes arranged block. The ferrule and the wire conductors are disposed within a peripheral opening, the underside of the ceramic heater formed on one edge. The apparatus further comprises a metallic clamping washer and a spring washer. The metallic clamping disk and the spring disk are also arranged within the edge opening, and the electrode block presses against the ferrule, and the ferrule presses against the clamping washer, and the clamping disk presses against the spring washer.

In a further aspect the invention provides a method generally for wafer bonding, comprising. Firstly, providing a lower jig, the adapted, to support a first wafer. Next, providing an upper jig, the adapted, to support a second wafer. The second wafer is arranged opposite the first wafer. Next, providing a process chamber, formed between the upper chuck and the lower jig. Next, providing three adjusting mechanisms, disposed around a top cover at an angle of from each other and arranged outside the process chamber around 120 deg are. Each adjustment mechanism comprises a component for sensing contact with the upper jig, a component for adjusting the biasing force of the upper jig and a component for leveling the upper jig. The method further comprising adjusting the preload force and the leveling the upper chuck and manual then guiding the contact with the upper jig on a computer application. The computer application adapted, and positions of the three adjustment mechanisms provide images on a display and movement of the upper jig to control and guide the component for sensing a contact via. When a contact with the upper jig is detected, the images on the light adjusting mechanisms, where the contact took place.

In a further aspect the invention provides a wafer generally bonding apparatus, comprising: a lower jig to support, the adapted, a first wafer, and an upper jig, the adapted, to support a second wafer, so that the second wafer is disposed opposite said first wafer. A process chamber is formed between the upper jig and the lower jig, and the lower chuck is an electrostatic chuck. The electrostatic chuck comprises a ceramic heater with integrated heating wires, a thin dielectric layer on a surface of the ceramic heater and electrical interconnections. The electrical interconnections comprise an electrode block and a wire conductor, surrounded by a ferrule, and the electrode block is brazed to a bottom surface of the ceramic heater and is arranged on the top of the ferrule. The electrode block, the ferrule and the wire conductors are disposed within a peripheral opening, the underside of the ceramic heater formed on one edge. The apparatus further comprises a metallic clamping washer and a spring washer, and the metallic clamping disk and the spring disk are also arranged within the edge opening. The electrode block presses against the ferrule, and the ferrule presses against the clamping washer, and the clamping disk presses against the spring washer.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the following description. Further features, functions and advantages of the invention will become evident from the following description of the preferred embodiments from, the drawings and the claims.

Brief description of drawings

We turn now Figures, identical reference symbols designate identical parts in the various views where always:

FIGURE. 1 shows a cross-section diagram of a temporary bondermoduls;

FIGURE. 2 shows a temporary bonding module according to this invention;

FIGURE. 3 shows a cross-sectional view of the wafer of fig. temporary bonding module. 2 filling direction perpendicular;

FIGURE. 4 shows a cross-sectional view of the wafer of fig. temporary bonding module. 2 along the filling direction;

FIGURE. 5a shows a wafer centering device having the advance direction in the closed position arms;

FIGURE. 5b shows the recess locator mechanism, the centering device of FIG in the wafer. 5a is used;

FIGURE. 300 mm wafers 5c shows a, wherein the recess engages into the wafer recess completely finders;

FIGURE. 300 mm wafers 5d shows a, wherein the recess engages into the wafer recess not fully finders;

FIGURE. 6 shows a cross-sectional view of the upper chuck of the temporary wafers bonding module from Figure. 2;

FIGURE. 7 shows a perspective top view of the temporary wafers bonding module from Figure. 2;

FIGURE. 8 shows the upper lid of the temporary wafers bonding module from Figure. 2;

FIGURE. 9 the upper chuck of the temporary wafers bonding module from Figure shows. 2;

FIGURE. 10a shows the adjustment components of the upper jig of FIG. 9 away cover and the top cover in place with withdrawn;

FIGURE. 10b shows the adjustment components of the upper clamping device of FIG. 9 withdrawn away with anticipated upper lid cover and away;

FIGURE. 11a is a perspective view of the components of the upper jig setting of FIG. 9;

FIGURE. Figure 11b is a cross-sectional view of the adjustment components. 11A;

FIGURE. 12 is a further perspective view of the adjustment components of FIG. 11A;

FIGURE. 13 is a detailed cross-sectional view of the tension adjusting component, the clamping fixture localization component and the contact sensor component;

FIGURE. 14 is a detailed cross-sectional view of the leveling adjustment component and the contact sensor component;

FIGURE. 15 is a detailed cross-sectional view of the upper jig for alignment component;

FIGURE. 16 a detailed cross-sectional view of the tension attitude component; is

FIGURE. 17 a screenshot of application of wafer attitudes; is

FIGURE. 18a is a lateral cross-sectional view through the connection between the lower heating device and said electrostatic chuck the temporary bonding module of FIG. 2;

FIGURE. 18b is a top view of the portion a of the lower heater and the electrostatic chuck of the temporary bonding module of FIG. 17;

FIGURE. 19a is a magnified view of region a of Figure. 18B;

FIGURE. 19b is an enlarged lateral cross-sectional view of region a of Figure. 18B;

FIGURE. 20 is a cross-sectional view of region a of Figure. 18b; and

FIGURE. 21 is an exploded view of region a of Figure. 18B.

Detailed description of the invention

We are Figure. 1a Figure. 6 to. A temporary bonding wafers 212 a housing module, the 212a includes a top cover, a feed door 211, an upper block assembly 220 and 230 210 has an opposite lower block assembly comprises. The upper and lower block assembly 220, 230 are movable with four Z guide pillars connected 242. A telescopic curtain seal disposed between the upper and lower block assembly 220 235, 230. A temporary bonding chamber 202 is between the upper and lower assembly 220, 230 and the telescopic curtain seal 235 formed. The curtain seal 235 isolated many of the process components, the temporary bonding chamber located outside the region 202, of temperature, pressure, vacuum and atmosphere of the process chamber. The region outside the chamber 202 to process components include such guide pillar 242, 243 Z-axis drive, illumination sources, mechanical advance direction arms 460a, 460b and wafer centering jaw 461a, 461b. In this embodiment the chamber 210 further three adjusting mechanisms 110a, 11 whether, 110c, are located outside the bonding area chamber 202 and accessible from outside the upper lid comprises 212a are. The adjustment mechanisms 110a, 11 whether, 110c comprise components, contact of the substrate used for sensing, for adjusting the downward biasing of the chuck and for leveling an upper jig 222, as is described below still.

We are Figure. 3 to. The lower block assembly 230 comprises a heating plate (lower jig) 232, the supports the wafer 20, an insulating layer 236, a water-cooled support flange 237, a transfer pin step 238, 240 and a Z-axis block of the transfer pins 239. The hot plate is a ceramic plate 232 and 233 and 234 comprises resistance heating elements an integrated air cooling. The heating elements 233 are so arranged, that two different heating zones are formed. A first heating zone 233b is designed, a 200 mm wafer or 300 mm wafer to the center region of a heating, and a second heating zone 233a is adapted, the peripheral edge of the 300 mm wafer to heating. The heating zone is controlled independently of the heating zone 233a 233b, to achieve a thermal uniformity across the bonding interface between two stacked wafers and thermal losses at the edges of the wafer stack to reduce. The hot plate 232 further comprises two different wafers of 200 mm or 300 mm vacuum zones for holding. The water-cooled thermal insulating support flange 236 237 is separated from the heating plate by the insulating layer. The transfer pin step 238 is arranged below the lower block assembly is supported movably on the four pillars 230 and 242. The transfer pin stage 238 240 supports the transfer pins, arranged such, that it may raise wafers of different sizes and lowering. The transfer pins are arranged in a example 240, 200 mm and 300 mm wafers - that it can be raised and lowered. The transfer pins are straight shafts and in some embodiments a vacuum 240 vent opening, extending through its center. A vacuum holds the wafers produced by the transfer pin apertures based on the transfer pins in place during movement and prevents misalignment of the wafer. The Z-axle pad 239 comprises a Z-axis precision drive with ball screw 243, a linear cam designs, a linear encoder feedback position control and a servo motor with a gearbox for submicron 244 246, as indicated in Figure. 4 is shown.

We are Figure. 6 to. The upper block assembly 220 comprises an upper ceramic chuck 222, an upper static chamber wall 221, 235 with a sealing member seals against the curtain 235a, a 200 mm membrane layer 224a and a 300 mm membrane layer 224b. The membrane layers 224a, 224b are between the upper jig and the upper housing wall 213 with terminals 215a or 215b 222 clamped and forming two separate vacuum zones 223a, 223b, adapted, 200 mm or 300 mm wafer - holding. The membrane layers 224a, 224b are made of elastomeric material or metal bellows. The upper ceramic chuck 222 is extremely flat and thin. It has a low mass and is semi-flexible, the stacked wafers 20, 30 to apply with a uniform pressure. The upper jig 222 is biased slightly with the three adjusting mechanisms 110a, 11 whether, 110c. The adjustment mechanisms 110a, 11 whether, 110c are arranged at intervals of 120 deg circular and are used, adjust the biasing force of the clamping device, to detect the contact or bonding the substrates and the height of the upper jig set 222 relative to the lower clamping device 232. The upper jig 222 is first levelled, while in contact with the lower chuck 232, such that it lies parallel to the bottom clamping device 232.

Loading the wafer with the mechanical centering device 460 prealigning and enabling, listed in FIGS. 5a is shown. The centering device comprises two rotatable arms 460 advance direction 460a, 460b and a linearly moving alignment arm 460c, in Figure. 5 shown in the closed position. At the ends of each arm 460a, 460b there are mechanical jaws 461a, 461b. The mechanical jaw 461a, 461b 462 and 463 have tapered surfaces, the curved edge of the 300 mm wafer 200 or the corresponding mm wafer. The linearly moving arms has a curved inner surface with a tapered jaw 461c 460c, also corresponding to the curved edge of circular wafers. The jaw mechanism further comprises a locator recess 461c, 469 of the recess located, at the curved edge of the circular wafer formed. Rotating the arms 460a, 460b 464 465 toward the center of the jig and the linear movement of the arm toward the center of the jig 464 465 460c brings the tapered surfaces of the mechanical jaws 461a, 461b and the tapered curved inner surface of the jaw in contact with the outer peripheral edge of the wafer and centered 461c the wafer in the chuck 464. The three arms 460a, 460b, 460c are arranged at distances of 120 deg around the chuck 464. In another embodiment the tracking assembly 460 comprises three rotatable advance direction arms, and at the ends of each arm jaws are mechanical. A rotating the arms toward the center of the jig 464 brings the tapered surfaces in contact with the outer peripheral edge of the wafer the mechanical jaws and centered in the wafer chuck 464. Other embodiments for loading and prealigning the wafer in the US patent application with the serial number are 12/761, 044, lodged on 15 april 2010, entitled "wafer Vorrichtung zur cENT RING" described, hereby expressly included by reference to the document content.

We are Figure. 5b to. The recess comprises a recess 470 472 who knows who knows mechanism, a position sensor 476, a floating hinge joint 477, 478 nasal carriage rollers, movement cam plate 479, 480 compartment a service loop, a piston or motor 474 and front plates 488. The front plate support the reel nasal carriage 488 478. The recess comprises an elongate component and a triangular component 472 finders 473a 473b. The elongated component forms the base of the triangular component partially 473a 473b. The elongated component further comprises three projections 473a 472a, 472b, 472c, extends from the front side of the component and extend 473a formed such, that they correspond to the form of the wafer on the wafer or a flat structural element 469 recess peripheral edge. For the case of a wafer having a flat structural member on the wafer peripheral edge and lateral projections are a small piece before the central projection 472a 472c 472b and are used, to locate the flat structural element of the substrate. The recess is driven by a piston or motor 474 472 finders forward, and the relative distance between the rear side and the front side of the component 486 487 488 473a 488a the front plate is measured with the position sensor 476, as

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this in Figure. 5c is shown. In a example of the position sensor is a linear potentiometer 476. The floating hinge joint connecting the front of the position sensor with the back of the 476 477 473a component. The nasal carriage rollers comprises rollers 478 478a, 478b, roll along the peripheral edge of the wafer, as in this Figure. 5c and Figure. 5d is shown. The relative distance is measured from the front side of the front panel from 488a 486 488, around wafer having various sizes (200 mm and 300 mm wafers - i.e.) permit, since the recess engagement positions for different wafer sizes are not the same. In a example, a complete engagement between the projection and the recess when in a 300 mm wafers is 472b 469, the 486 6.77 mm distance is, as indicated in Figure. 5c is shown. If no full engagement between the projection and the recess is 472b 469, the distance 486 (i.e. is 6.02 mm) smaller, as indicated in Figure. 5d is shown. This distance measurement is used, to confirm, a full engagement between the recess and the recess 472 who knows whether 469 in the wafer 20 is or not.

We are Figure. 7a Figure. 16 to. The chamber 210 comprises an upper cover 212a, removably coupled to the top 109 of the chamber 210 with screw 109. As suggested above are three adjustment mechanisms 110a,, 110b, 110c are arranged outside the process chamber area 202 and accessible from outside the top lid 212a. Each adjusting mechanisms 110a, 11 whether, 110c comprises a removable cover 111 and components, the 130 for sensing a contact, for adjusting the tension of the upper jig 222 120 140 and the leveling are used. As indicated in Figure. 10a is the cover is shown, removed 111, and the adjustment elements 122, 132, 142 of the three components 120, 130 or 140 are exposed, so that they can be operated from above set, about leveling, contact and voltage of the upper chuck 222. All settings can be made, while the chamber vacuum or atmospheric pressure 210.

We are Figure. 10b to Figure. 12 to. The adjusting mechanism 110a comprises a leveling adjustment component 120, 130 and a voltage adjustment component 140 a contact detection component. As in Figure. 11b shown, allows the design of the push-through components 150 by vacuum seal cover 114, the corresponding adjusting elements and sensors 122, 132, 142 arranged outside the process chamber can be 202. Each adjustment mechanism further comprises a load cell 160 for accurately measuring the bias force of the jig 222, as in Figure. 11a shown. In Figure. 11b is also shown jig alignment pin 240, is guided by an improved low friction bearing.

As in Figure. 12 and Figure. 14 shown, comprises the leveling component 120 a leveling adjustment fine measuring screw 122, a screw shaft and a screw locking clamp vernier vernier 126 124. The vernier screw 122 has a resolution of 1 micrometer, and the locking clamp 124 is used therefor, to lock the position of the vernier screw, after being adjusted to a desired level. The vernier screw shaft 126 extends through an opening in a support plate 115 and has a distal end 126a, the contacts an end of a pivot arm 116a 116. The pivot arm 116 is coupled via the pivot point 118 on the support plate 115. The end 116a further comprises the load cell 160, which is used for accurately measuring the biasing force of the clamping device. The opposite end of the pivot arm 116 is connected to a push-through shaft 138 116b of the contact sensor 132. The 138 by pusher shaft which passes through an aperture, which is formed at the end of the pivot arm 116b. The contact detection component 130 comprises a contact sensor 132, is operated via a 24 V to signal, 134 and 136 is a ground provided by the cable. The contact sensor 132 is connected to the push-through shaft 138, which is surrounded by a bellows 137. The contact detection component 130 and a biasing spring and a ball bearing a contact guide 135 133 interface further comprises. The ball bearing interface 133 contacts a thrust washer 131, by pusher shaft and supported by said pivot arm 138 surrounding the end 116b is. The distal end of the pusher shaft 138a 138 is rigidly attached on the top face by chuck 222. The thrust shaft 138 is made of a material with low coefficient of thermal expansion by (temperature coefficient of thermal spring expanding, CTEs). In a example 138 by pusher shaft is made of Invar. A thermal insulation between the upper jig 222 by pusher shaft provided via thermal break points 138 and 166.

Rotating the vernier screw 122 clockwise moves the vernier screw shaft 126 downward along the direction 127a. As suggested above, the distal end of the screw shaft with the end 126 is vernier 126a 116a of the pivot arm 116 connected, around the pivots about the pivot point 118. Moving the vernier screw shaft 126 moves the end of the pivot arm 116 downwardly along the direction 127a 116a and the end 116b down upward. Since the end of the pivot arm 116 is connected to the pusher shaft 138 by 116b, the upward movement of the end 116b moves the pusher shaft upward along the direction 139a by 138. Rotating the vernier screw 122 counterclockwise moves the vernier screw shaft 126 upward along the direction 127b. Moving the vernier screw shaft 126 upward along the direction moves the end 116a of the 127b

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Pivot arm 116 upwardly and the end 116b down. The downward movement of the end 116b moves the thrust shaft 138 by downward along the direction 139b. When the upper jig 222 and moves the distal end 138a 138 by pusher shaft, which is rigidly attached to the upper jig 222, through which approximate lower jig or lower chuck, which holds a substrate, are upward, so that the contact sensor registered a signal 132.

We are Figure. 15 to. Each alignment pin chuck 240 is passed over a sophisticated low friction bearing. The low-friction bearing comprises a base block 172, surrounds a ball bearing bushing 170, 171 a ball bearing housing and a moving guide shaft 174. The pins 240 further comprise jig holding members 176, 179 blocks contact the upper clamping fixture localization. Each pin 240 further comprises a guide pin opening 177.

We are Figure. 16 to. The voltage adjustment component 140 comprises a screw 142, rotated, adjust the upward tension of the jig 222, by a tension spring 144 is pushed together or pulled apart along the direction 145. The screw 142 148 comprises a plug, and a swivel bearing housing supported within said through hole 142b has 149. The pivot bearing retainer 149 147 holds a pivot bearing. The pivot bearing has a hook at the distal end 147 147a, detects a sheet at the proximal end of the spring 144 144b. The distal end of the spring 144 144a has a hook, the hook engages, is formed in a spring anchor 141a, a block is arranged in the upper clamping fixture localization 141. The screw 142a 142 comprises an external thread, which is so arranged and constructed, that it takes an internal thread engaged 158a, 158 formed in the inner walls of the push-through opening, the 152 in the base block and the seal cover is formed 114. Upward movement of the tension spring 144 is limited by circular clips 146.

During operation are controlled leveling, and positioning the upper jig 222 by the levelling - voltage, voltage - and contact components of the three adjusting mechanisms 110a, 11 whether, 110c. In one embodiment the levelling voltage components are adjusted manually by rotating the vernier - and screw the screw 122 or 142, and the contact is guided via a computer application 50. We are Figure. 17 to. A screen 51 the computer application 50 comprises a picture of the three contact sensors 52 b, b is, c is in the corresponding adjustment mechanism 110a, 11 whether, 110c, position 54, 56 and 57 of the delta value of the average value.

The upper jig 222 is adjusted, to move to a level, which is set in the block portion 58, and then the contact is over the contact sensors in the adjusting mechanisms 110a, 11 whether, 110c guided. If the two wafer contact 20, 30 each other, the upper jig 222 moves upward, whereby the sensor 132 136 separates from the ground, and thus the contact sensor registered a signal 132. A signal when the sensor 132 registered, so that the picture of the corresponding sensor 52 a is illuminated, b is, C on the screen 51. The speed of movement slowed down from a user defined distance from the contact position of the upper jig's estimated. In the example of FIG. 17 the upper jig 222 is adjusted, to move a contact position 59 of 13400 micrometers. The thickness of the two-wafer stack 62, including the adhesive, is 1700 micrometer. The thickness of the wafer stack from the contact position subtracting leads to a final position 61 of 11700 micrometers. The application has to the control unit 50, to a configurable "proximity" - position to go, and then they used a configurable movement with lower velocity, by the sensors to a contact of a, b and c is detected. The contact position for each sensor is displayed in columns 54, the average delta in column 57 in column 56. In other embodiments the levelling voltage components are also adjusted on the computer application - and 50.

We are Figure. 18a to Figure. 21 to. In one embodiment the lower block assembly 230 includes electrostatic lower heater on tensioning device 232. The electrostatic chuck holds the wafer 20 in a safe locked position and prevents 232 inadvertent wafers due to vibrations, thermal expansion or gas, flowing in the chamber. The electrostatic chuck 232 comprises a ceramic heater with integrated heating wires and a thin dielectric layer 270 on the top. Electric current is fed to the electrostatic chuck 232 260 via electrical interconnections. In this embodiment the electrode block 262 and a wire conductor 260 electrical interconnections comprise a 263, 264 surrounded by a ferrule. The electrode block 262 is brazed to the underside of the ceramic heater is disposed on the top of the ferrule 232 and 264 and the conductor 263. The block 262, 263 267 264 and conductor sleeve are housed in a opening, which is formed on the edges and below the lower chuck surface, as indicated in Figure. 19b is shown. The block 262 263 presses against the conductor, and the conductor 263 presses against a metal clamping washer 265, at the bottom of the

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Opening 26 is arranged. The metallic clamping washer presses against a wave spring washer 266.

Various embodiments of the present invention have been described. Despite it is understood, that various modifications can be made, without departing from the nature and scope of the invention depart. Other embodiments are within the scope of the following claims accordingly.