Spacer adjustment device for a wafer exposure unit and wafer exposure unit

Abstract

Spacer adjustment device (30) for a wafer exposure unit (10), comprising an actuator (34), a spacer (32) which can be adjusted by the actuator (34) between an active and an inactive position, and a force transmission element (48) which is coupled to the actuator (34), characterized in that the force transmission element (48) is made of wire.

Description

[0001] The invention relates to a spacer adjustment device for a wafer exposure unit, comprising an actuator, a spacer that can be adjusted by the actuator between an active and an inactive position, and a force transmission element coupled to the actuator. The invention also relates to a wafer exposure unit with such a spacer adjustment device.

[0002] A wafer exposure unit can be used in a photolithography process to expose a photoresist applied to the wafer. The exposure occurs through a mask, so that, according to the shadow cast by the mask, certain areas of the photoresist are not exposed. Depending on the exposure, the physical properties of the photoresist change, allowing it to be partially removed in a subsequent step, leaving a (positive or negative) photoresist image of the mask on the surface of the wafer.

[0003] DE 10 2010 007 970 A1 describes a method and a device for extending the available travel of linear actuators during the embossing stroke. The wedge error compensation head has a moving part, a stationary part, and at least three linear actuators. To perform a precise reference measurement and wedge error compensation, the moving part of a wedge error compensation head is measured and aligned using probes, sensors, and inserted distance flags. Coarse compensation is achieved via pneumatically actuated wedges, and fine compensation is achieved by linear actuators to maximize the remaining travel for the embossing stroke.

[0004] JP 2010-113296 A describes a proximity exposure system. It further describes a device that places a protective spacer on the chuck before the mask is inserted. The spacer is held over the chuck, lowered, and then the device returns to its standby state.

[0005] US 2008 / 0188069 A1 describes an imprint lithography device in which spacers are inserted between an imprint mask and a wafer by means of movable arms for the purpose of aligning the mask and wafer parallel to each other.

[0006] US 2008 / 0213418 A1 describes a wafer processing device in which a wafer is fixed by means of swiveling clamps and spacers.

[0007] US 2007 / 0210261 A1 describes a wafer holding device for an electron beam lithography system in which a wafer is fixed by means of movable pins.

[0008] The wafer can then be processed in subsequent steps to create three-dimensional structures. In this way, for example, semiconductor chips or MEMS (microelectromechanical systems) can be produced.

[0009] For correct exposure of the photoresist, it is important that the mask is positioned at a precisely defined distance from the wafer. Several spacers can be used for this purpose; when needed, they are moved from the inactive to the active position by the spacer adjustment device to position the mask.

[0010] A known wafer exposure unit 10 with the spacer adjustment devices used therein is described in the Fig. 1 and Fig. Figure 2 shows that a total of three spacer adjustment devices 12, 14, 16 are attached to a base body 11 of the wafer exposure unit. Each of these contains an actuator 18 to which a swivel arm 20 is assigned. A spacer (not shown here), for example a spacer ball (“proximity ball”) or a disc, a roller, etc., is attached to the free end of the swivel arm 20, which is opposite the pivot axis.

[0011] To remove the swivel arms 20 from the in Fig. 1 shown inactive position into the in Fig. To adjust the active position shown in Figure 2, each actuator 18 has a rack that engages a gear segment 22, which is mounted concentrically to each pivot arm 20 on its pivot axis. When the rack is moved translationally within the actuator 18, this results in a pivoting movement of the pivot arm 20.

[0012] The known design is comparatively complex.

[0013] The invention is therefore based on the objective of creating a spacer adjustment device that is simpler in design and works more reliably.

[0014] To solve this problem, the invention provides that, in a spacer adjustment device of the type mentioned above, the force transmission element consists of wire. Such a force transmission element makes it possible to transfer an adjustment movement of the actuator directly to the spacer without the need for complicated and costly gears. By eliminating the rack, the risk of the rack becoming clogged by materials used in the photolithography process or in the manufacture of the spacer adjustment unit is eliminated.

[0015] Preferably, the wire is straightened wire, meaning wire that has no bending whatsoever when unloaded and extends straight. This allows for high precision.

[0016] According to one embodiment of the invention, the spacer is attached to a pivoting element. This makes it possible to translate a comparatively small stroke of the actuator into a comparatively large adjustment range of the spacer, provided that the spacer is mounted at a correspondingly large distance from the pivot axis of the pivoting element.

[0017] Preferably, the swivel element is coupled to the wire in order to convert the stroke of the actuator into a swiveling movement of the swivel element without intermediate elements.

[0018] The wire can be hooked into an opening of the swivel element, so that a reliable coupling is achieved with minimal assembly effort.

[0019] Preferably, the spacer is attached to a support arm that is connected to the swivel element. This creates a modular design, allowing different support arms to be attached to the same swivel element.

[0020] According to one embodiment of the invention, the holding arm is made of wire. This results in a cost-effective design.

[0021] The spacer can be attached directly to the wire. This also results in lower manufacturing costs. In particular, the spacer can be threaded onto the wire and glued in place. This creates a small surface area at the glued joint for aggressive chemicals used in photolithography processes.

[0022] In order to adapt the spacer adjustment device to different applications with minimal effort, the holding arm is preferably attached to the swivel element in a height-adjustable manner.

[0023] For this purpose, according to one embodiment, several openings at different heights can be provided in the swivel element, in which the holding arm can be positioned. The openings ensure reliable guidance of the holding arm in every position.

[0024] Alternatively, the swivel element can be provided with a notch in which the support arm can be fixed at different heights. This allows the support arm to be adjusted (almost) continuously in height.

[0025] In order to reliably fix the holding arm in the swivel element, but to be able to easily remove it and remount it in a different position if necessary, a fixing screw is preferably provided with which the holding arm can be clamped in the swivel element.

[0026] According to a preferred embodiment of the invention, an adjustment element is provided which interacts with the pivoting element. This makes it possible to adjust the position of the spacer in the active position immediately and directly.

[0027] The adjustment element can be designed to interact with a stop surface. This results in reduced assembly effort and high accuracy, as no intermediate components are required.

[0028] According to an alternative embodiment, a deflection device is provided which is arranged between the actuator and the spacer and engages the wire. In this design, the stroke of the actuator is directly converted into a corresponding stroke of the spacer, without the need for intermediate coupling elements.

[0029] According to one embodiment of the invention, the deflection device has several deflection rollers. This makes it possible to deflect the wire with low friction.

[0030] According to an alternative embodiment, the deflection device is provided with a guide channel. This variant is characterized by low assembly effort.

[0031] According to one embodiment of the invention, the actuator has a piston to which the wire is coupled. This directly translates a stroke of the piston into a stroke of the wire.

[0032] The piston can define a pressure chamber that can be pressurized with a pressure medium. This allows the piston to be adjusted with minimal effort by applying, for example, a vacuum or compressed air to the pressure chamber.

[0033] It is also conceivable that the piston is adjusted electromagnetically.

[0034] Preferably, an adjusting element is provided to define the pressure chamber, with which the piston's initial position can be adjusted. This allows the position of the spacer to be precisely adjusted in the inactive position.

[0035] According to one embodiment of the invention, a return spring is provided. This ensures that the spacer is automatically returned to its initial position when the actuator is no longer activated.

[0036] The return spring can act specifically on the piston. This results in a compact design with low friction.

[0037] The invention also relates to a wafer exposure unit with such a spacer adjustment device. Regarding the advantages arising therefrom, reference is made to the explanations above.

[0038] The invention is described below with reference to two embodiments, which are illustrated in the accompanying drawings. The drawings show: - Fig. 1 a wafer exposure unit with spacer adjustment device according to the prior art, wherein the spacer is in an inactive position; - Fig. 2 the wafer exposure unit of Fig. 1, wherein the spacer is in an active position; - Fig. 3 a spacer adjustment device according to a first embodiment of the invention in a partially cutaway view, wherein the spacer is in an inactive position; - Fig. 4 the spacer adjustment device of Fig. 3, wherein the spacer is in an active position; - Fig. 5 a spacer adjustment device according to a variant of the first embodiment in a partially cutaway top view, wherein the spacer is in an inactive position; - Fig. 6 the spacer adjustment device of Fig. 5 with the spacer in an active position; - Fig. 7 the spacer adjustment device according to Fig. 5 in another section plane; - Fig. 8 the spacer adjustment device according to Fig. 6 in the section plane of Fig. 7; - Fig. 9 the spacer adjustment device of the Fig. 7 and Fig. 8 in a different adjustment state; - Fig. 10 in a cutaway side view the spacer adjustment device of the Fig. 5 to 9; - Fig. 11 a variant to the in Fig. 5 spacer adjustment device shown, wherein the spacer is in an inactive position; - Fig. 12 in a perspective view an adjusting element for a spacer adjusting device according to the Fig. 5 to 11 with a holding arm for the spacer, which is located in a middle position; - Fig. 13 the adjusting element of Fig. 12 in one cut; - Fig. 14 in a perspective view the adjusting element of Fig. 12, wherein the holding arm is in a lower position; - Fig. 15 the adjusting element of Fig. 14 in one cut; - Fig. 16 in a perspective view an adjustment element in an alternative design variant, wherein the holding arm is mounted in a lower position; - Fig. 17 the adjusting element of Fig. 16 in one cut; - Fig. 18 in a perspective view the adjusting element of Fig. 16, with the holding arm in a middle position; - Fig. 19 the adjusting element of Fig. 18 in one cut; - Fig. 20 in a perspective, greatly enlarged view, one during the configuration of the Fig. 18 and Fig. 19 height adjustment part used; - Fig. 21 a spacer adjustment device according to a second embodiment of the invention in a perspective view; - Fig. 22 the spacer adjustment device of Fig. 21 in a sectional view; - Fig. 23 a spacer adjustment device according to a variant of the second embodiment.

[0039] In Fig. Figure 3 shows a spacer adjustment device 30, with which a spacer 32 can be moved from an inactive position, which is in Fig. As shown in 3, it can be adjusted to an active position, which is in Fig. 4 is shown.

[0040] The spacer 32 is a sphere that can be used to position a mask at a predefined distance relative to a wafer in a wafer exposure unit, such as those used in photolithography processes.

[0041] The spacer adjustment device 30 has an actuator 34 with which the spacer 32 can be adjusted.

[0042] During the Fig. 3 and Fig. In the embodiment shown in Figure 4, the actuator 34 includes a piston 36 which is adjustably arranged in a cylinder 38. The cylinder 38 is provided in a base body 40 of the actuator 34.

[0043] The spacer 32 is attached to a holding arm 42, which in turn is attached to a pivoting element 44. The pivoting element 44 is pivotably mounted in the base body 40 about an axis 46.

[0044] The retaining arm 42 is designed here as a long, straight rod, which can be made of metal, for example, especially wire. It is connected to the swivel element 44 in such a way that it is adjusted when the swivel element 44 is rotated. The retaining arm 42 can, for example, be clipped into a receptacle of the swivel element 44.

[0045] The pivoting element 44 is connected to the piston 36 by means of a force transmission element 48 made of wire. In the embodiment shown, straight wire is used.

[0046] The power transmission element 48 is pivotably connected to the pivot element 44. In the illustrated embodiment, a bent end section of the power transmission element 48 is hooked into an opening of the pivot element 44. The connection is thus similar to the connection between a bicycle spoke and a hub, where a bent end of the spoke is hooked into an opening of the hub.

[0047] The end of the force transmission element 48 facing away from the pivoting element 44 is connected to the piston 36 in a tensile and compressive manner. The piston 36 can, for example, have a central opening into which the force transmission element 48 is inserted.

[0048] In cylinder 38, a return spring 50 is arranged on the side of the piston 36 facing away from the pivoting element 44, which moves the piston 36 into the Fig. The starting position shown in 3 is applied, in which the spacer 32 is in the inactive position.

[0049] The cylinder 38 is connected to a pressure medium connection 52, so that a pressure chamber formed in the cylinder 38, which is closed at one end by the piston 36, can be pressurized in a controlled manner.

[0050] To remove the spacer 32 from the in Fig. 3 shown inactive position in the in Fig. To adjust the active position shown in section 4, the pressure chamber in cylinder 38 is connected to a vacuum via the pressure medium connection 52. This causes the piston 36 to move against the action of the return spring 50 relative to the Fig. 3 and Fig. 4 is adjusted upwards. This stroke is transferred via the force transmission element 48 to the pivoting element 44, which accordingly (together with the spacer 32) performs a pivoting movement in a clockwise direction.

[0051] To return the spacer 32 to its inactive position, the pressure chamber inside the cylinder 38 is vented via the pressure medium connection 52. This causes the piston 36 to return to its starting position under the action of the return spring 50, thereby pivoting the pivoting element 44 counterclockwise.

[0052] The force transmission element 48 transmits the stroke of the piston 36 directly and almost frictionlessly to the pivoting element 44. Due to its inherent elasticity, the force transmission element 48 can absorb the slight lateral deflection that the connection point between the pivoting element 44 and the force transmission element 48 experiences when the pivoting element 44 is moved between the inactive and active positions, without subjecting the piston 36 to a disruptive tilting moment.

[0053] In the Fig. Figures 5 to 10 show a variant of the first embodiment of the spacer adjustment device. The same reference numerals are used for the components known from the first embodiment, and reference is made to the explanations above.

[0054] The essential difference between the first embodiment and the variant of the Fig. The difference between 5 and 10 is that in the version variant, the piston 36 is not adjusted by means of a vacuum, but with compressed air (or alternatively a pressurized gas).

[0055] As in the Fig. 5 and Fig. As can be seen in Figure 6, the piston 36 and a locking element 39 are arranged in the cylinder 38. The return spring 50 is located on the side of the piston 36 exposed to the pressure port 52, i.e., between the piston 36 and the pivoting element 44.

[0056] When compressed air is supplied to pressure port 52, the piston is moved out of the Fig. 5 starting position shown in the Fig. The activated position shown in step 6 is transferred so that the spacer 32 is transferred from the inactive position to the active position.

[0057] The position of the spacer 32 in the inactive position can be adjusted by the locking element 39 engaging more or less deeply into the cylinder 38. For this purpose, the locking element 39 can be provided with an external thread that engages with an internal thread in the cylinder 38 in the base body 40.

[0058] The position of the spacer 32 in the active position can be adjusted with an adjusting element 54 (see the Fig. 7 and Fig. 8) be adjusted so that it can interact with the swivel element 44.

[0059] In the embodiment shown, a stop surface 56 is provided on the pivoting element 44, which abuts the adjusting element 54 when the spacer 32 and thus the pivoting element 44 are in the active position (see Fig. 8).

[0060] The adjusting element 54 can be provided with an external thread in a similar manner to the locking element 39, which engages in an internal thread in the base body 40.

[0061] As in Fig. As can be seen in Figure 8, the adjusting element 54 not only ensures that the spacer 32 is adjusted by exactly 90° between the inactive and active positions, but also allows other swivel angles to be set. Here, the adjusting element 54 is screwed further into the base body 40, so that the swivel angle of the spacer 32 is smaller than in the figure shown in the Fig. 7 and Fig. Variant 8 shown.

[0062] In Fig. Figure 10 shows that the pivoting element 44 is cylindrical and its circumferential surface is inserted into a cylindrical receptacle 57 in the base body 40. The stop surface 56 forms the bottom of a groove 58 that extends to a certain depth into the pivoting element. The retaining arm 42 is clipped into a receptacle 59 provided on the pivoting element 44.

[0063] In Fig. Figure 11 shows another variant of the spacer adjustment device. The difference to the one shown in the Fig. The variant shown in 5 to 10 consists in the fact that a cover element 41 is attached to the base body 40, which is provided with a recess 43.

[0064] The cover element 41 represents an extension of the base body 40 such that the spacer, when attached to a very long support arm 42, does not protrude freely from the spacer adjustment device 30 and is unprotected, but is "parked" in the cover element 41. Here, it and the spacer 32 are very well protected from mechanical stresses and possible contamination.

[0065] The cover element 41 is detachably attached to the base body 40 by means of a screw 45. This allows the adjustment device to be modularly adapted to different design requirements.

[0066] With regard to different configurations and applications, it is desirable to be able to adjust the holding arm 42, and thus the spacer 32, to different heights. The swivel element 44 can be used for this purpose with minimal effort.

[0067] In the Fig. 12 and Fig. Figure 13 shows an embodiment of the pivoting element 44 suitable for adjusting the height of the support arm 42. The pivoting element 44 is provided with several openings 80 extending inwards from the cylindrical surface of the pivoting element 44.

[0068] In the embodiment shown, the openings 80 extend in a radial direction. However, it is also possible for the openings 80 to extend obliquely to a radial orientation.

[0069] A total of four openings 80 are used here, all arranged one above the other. This makes it possible to position the retaining arm 42 (and thus the spacer 32) at a desired height (compare the Fig. 12 and Fig. 13 on the one hand, in which the holding arm 42 is arranged in one of two middle positions, with the Fig. 14 and Fig. 15 on the other hand, in which the holding arm is in a lower position).

[0070] To fix the retaining arm 42 in the selected opening 80, a fixing screw 82 can be used, which is screwed into a clamping bore 84 until the retaining arm is reliably secured. If desired, in cases where the retaining arm 42 is not in the lowest position, a spacer 86 can be used (see Fig. 13) are placed underneath.

[0071] In the Fig. 12 and Fig. A notch 90 can also be seen in 14, into which two passages 92 open. The force transmission element 48 is coupled to the pivot element 44 there, for example by clipping a ball head of the force transmission element into the recesses that are present at the intersection of the passages 92 with the notch 90.

[0072] In the Fig. 16 and Fig. Figure 17 shows a variant of the swivel element 44 in which the holding arm cannot be adjusted in steps in height, as is the case in the embodiment of the Fig. 12 to 15 is the case, but (almost) continuously.

[0073] For this purpose, a receiving channel 94 is provided in the pivoting element, which extends through the pivoting element 44 in the same orientation as all the openings 80. In the embodiment shown, the receiving channel is designed as a cut extending diametrically from the top surface through the pivoting element, ending just above the bottom surface of the pivoting element.

[0074] The retaining arm 42 is inserted into the receiving channel 94 and fixed there with a fixing screw 82. This engages in a thread provided in a clamping bore 84 that intersects the receiving channel 94.

[0075] When the retaining arm 42 is fixed in its lowest position, the fixing screw 82 clamps the retaining arm against the bottom of the receiving channel 94 (see the Fig. 16 and Fig. 17).

[0076] If the support arm is to be fixed in a higher position (see the Fig. 18 and Fig. 19), a height adjustment element 96 is inserted into the clamping channel and / or the clamping bore 84, which is supported on the bottom of the clamping channel and on which the retaining arm 42 then rests. The fixing screw 82 then clamps the retaining arm against the top of the height adjustment element.

[0077] In Fig. Figure 20 shows an embodiment of a height adjustment element 96. This is a cylinder whose outer diameter corresponds approximately to the inner diameter of the clamping bore 84. On its upper side, the height adjustment element is provided with a semi-cylindrical receptacle 98, so that the retaining arm 42 is received there over a flat surface.

[0078] The height adjustment part 96 can be stored in a variety of different heights, so that the support arm can be mounted very precisely at the desired height.

[0079] In the Fig. 21 and Fig. Figure 22 shows a second embodiment. The same reference numerals are used for the components known from the first embodiment, and reference is made to the explanations above in this respect.

[0080] The difference between the first and second embodiments is that in the second embodiment the spacer 32 is not adjusted rotationally, but translationally.

[0081] In the second embodiment, the spacer 32 is attached to the force transmission element 48. Here, too, the force transmission element 48 is formed by a directed wire. This wire is guided from the piston 36 of the actuator 34 via a deflection device 60. The deflection device 60 allows the spacer 32 to be adjusted between the inactive and active positions in a direction that differs from the stroke direction of the piston 36. This can be advantageous in cases of limited installation space.

[0082] In the illustrated embodiment, the deflection device 60 consists of several deflection rollers 62, which deflect the power transmission device 48 by 90°. The deflection rollers 62 are arranged such that the power transmission element 48 is guided on a sufficiently large bending radius that does not result in any plastic deformation.

[0083] Between the deflection device 60 and the spacer 32, a wire guide 64 is provided, which additionally stabilizes the force transmission element 48 at the output of the spacer adjustment device 30.

[0084] Instead of deflection pulleys 62, a wire guide similar to a Bowden cable can also be used to guide and redirect the wire as desired. If a stop of the Bowden sheath is adjustable, the position of the spacer 32 can be easily adjusted in the direction of adjustment.

[0085] In Fig. Section 23 describes a variant of the second embodiment. The same reference numerals are used for the components known from the second embodiment, and reference is made to the explanations above in this respect.

[0086] The essential difference between the in Fig. 23 shown variant and embodiment of the Fig. 21 and Fig. 22 consists in the fact that at Fig. 23 The deflection device 60 does not have any deflection rollers, but is formed by a curved channel 70 which is provided in the base body 40. This deflects the force transmission element 48 from the adjustment direction of the piston 36 into the desired adjustment direction for the spacer 32.

[0087] Another difference is that, according to the spacer adjustment device... Fig. 23 the force transmission element is designed to be so short that the spacer 32 is “parked” in a recess 72 in the base body 40 in the inactive position. This is also fundamentally the case with the Fig. 21 and Fig. The embodiment shown in 22 is possible if the power transmission element 48 is made correspondingly shorter and the wire guide 64 is omitted.

Claims

[1] Spacer adjustment device (30) for a wafer exposure unit (10), comprising an actuator (34), a spacer (32) which can be adjusted by the actuator (34) between an active and an inactive position, and a force transmission element (48) coupled to the actuator (34), characterized by , that the power transmission element (48) consists of wire. [2] Spacer adjustment device according to claim 1, characterized by , that the wire (48) is a directional wire, wherein the wire (48) has no bending in the unloaded state and extends straight. [3] Spacer adjustment device according to one of the preceding claims, characterized by , that the spacer (32) is attached to a swivel element (44). [4] Spacer adjustment device according to claim 3, characterized by , that the swivel element (44) is coupled to the wire (48). [5] Spacer adjustment device according to claim 4, characterized by , that the wire (48) is hooked into an opening of the swivel element (44). [6] Spacer adjustment device according to one of claims 3 to 5, characterized by , that the spacer (32) is attached to a retaining arm (42) which is connected to the swivel element (44). [7] Spacer adjustment device according to claim 6, characterized by , that the retaining arm (42) is made of wire. [8] Spacer adjustment device according to claim 7, characterized by , that the spacer (32) is attached to the wire (42). [9] Spacer adjustment device according to one of claims 6 to 8, characterized by , that the holding arm (32) can be attached to the swivel element (44) in a height-adjustable manner. [10] Spacer adjustment device according to claim 9, characterized by , that the pivoting element (44) is provided with several openings (80) at different heights in which the holding arm (42) can be arranged. [11] Spacer adjustment device according to claim 9, characterized by , that the swivel element (44) is provided with a notch (90) in which the retaining arm (42) can be fixed at different heights. [12] Spacer adjustment device according to claim 10 or claim 11, characterized by , that a fixing screw (82) is provided with which the retaining arm (42) can be clamped in the swivel element (44). [13] Spacer adjustment device according to any one of claims 3 to 12, characterized by , that an adjusting element (54) is provided which interacts with the swiveling element (44). [14] Spacer adjustment device according to claim 13, characterized by , that the adjusting element (54) can interact with a stop surface (56). [15] Spacer adjustment device according to one of claims 1 and 2, characterized by, that a deflection device (60) is provided which is arranged between the actuator (34) and the spacer (32) and engages the wire (48). [16] Spacer adjustment device according to claim 15, characterized by that the deflection device (60) has several deflection rollers (62). [17] Spacer adjustment device according to claim 15, characterized by that the deflection device has a wire guide sheath. [18] Spacer adjustment device according to claim 15, characterized by that the deflection device has a guide channel (70). [19] Spacer adjustment device according to one of the preceding claims, characterized by , that the actuator (34) has a piston (36) to which the wire (48) is coupled. [20] Spacer adjustment device according to claim 19, characterized by , that the piston (36) defines a pressure chamber which can be pressurized with a pressure medium. [21] Spacer adjustment device according to claim 20, characterized by , that an adjusting element (39) is provided to define the pressure chamber, with which the initial position of the piston (36) can be adjusted. [22] Spacer adjustment device according to one of claims 19 to 21, characterized by , that a return spring (50) is provided. [23] Spacer adjustment device according to claim 22, characterized by , that the return spring (50) acts on the piston (36). [24] Wafer exposure unit (10) with a spacer adjustment device (30) according to one of the preceding claims.

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