TW201316133A - Step photolithography device and photolithography exposure method - Google Patents

Abstract

A step photolithography device and a photolithography exposure method thereof. The step photolithography device includes: an illumination unit (1) for providing an exposure beam, a workpiece station (4) for supporting a base (7) to move with six degree of freedom within a large journey range, a mask station (2) for supporting a mask (9) to move synchronously relative to the workpiece station (4) within a small journey range during exposure, and a projection objective (6) for projecting a pattern on the mask (9) to the base (7) according to a predetermined scale, wherein when the workpiece station (4) steps to an exposure field, the mask station (2) moves synchronously to a position corresponding to the workpiece station (4) and expose at the same time.

Description

Stepping photoetching device and photoetching exposure method

The invention relates to the field of integrated circuit equipment manufacturing, and particularly relates to a stepping photoetching apparatus and a photoetching exposure method.

A photoetching device is a device that exposes a reticle pattern onto a ruthenium wafer. Known photoetching devices include step-and-repeat and step-and-scan. In the stepper photoetching machine using the reduced magnification projection objective disclosed in the prior art, the magnification of the projection objective is reduced, that is, the reticle pattern is projected onto the substrate by the projection objective at a ratio of 1:N. The work piece table used in the stepping photoetching machine disclosed in the prior art generally adopts a structure in which a coarse motion structure is combined with a micro motion structure, or an XY (horizontal direction) motion stage is combined with a rotary table, or even A single coarse motion table structure. In the prior art, the photomask of the photoetching machine is a coarse motion stage.

The step exposure method in the prior art is that after the substrate is leveled and aligned, after stepping to the designated position on the workpiece table, the workpiece table needs to maintain a stable state of certain precision before exposure. With the conventional step-down projection device and method of reducing magnification, the step precision of the workpiece table is very high, and the stability time requirement is very short. For this reason, the whole unit is difficult and the capacity is seriously affected by the stabilization time. .

As shown in the contents of the technical solutions disclosed in the patents US2001/0021009, US6287735, and US2009/0201475, the above patents all adopt a reduced work piece table. The quality of the work piece, the structure of the work piece is simplified, and the control method is optimized to improve the stepping photoetching machine, but there are still defects of long time required for step stabilization and low yield.

The object of the present invention is to overcome the technical defects existing in the prior art, and provide a stepping photoetching apparatus and a photoetching exposure method, which can effectively reduce the step stabilization time, further reduce the total time required for exposure, and improve the yield of the photoetching apparatus. improve.

In order to achieve the above object, the present invention discloses a stepping photoetching apparatus comprising: an illumination unit for providing an exposure beam; and a workpiece stage for supporting a substrate to perform six-dimensional degrees of freedom motion in a large stroke range; a reticle for supporting a reticle to move synchronously with respect to the workpiece stage in a small stroke range during exposure; a projection objective for projecting the reticle pattern onto the substrate at a predetermined ratio; wherein the workpiece After the stage is sequentially stepped to the exposure field, the reticle stage is synchronously moved to the corresponding position of the workpiece table and exposed at the same time.

Further, the projection objective of the projection objective is 1:5.

Further, the stepper photolithography apparatus further includes a position measuring system.

Further, the horizontal moving device of the workpiece table is an H-shaped structure, and the vertical moving device is a cam mechanism.

Further, the horizontal movement device of the reticle stage is a Lorentz motor, and the vertical direction movement device is a reed mechanism.

Further, the position measuring system employs a laser interferometer or a coder.

Further, the reticle stage is synchronously moved to the corresponding XY and Rz positions of the workpiece table.

The invention also discloses a photoetching exposure method using the above stepping photoetching apparatus, comprising: step one, preparing for pre-exposure preparation; step two, after stepping the workpiece table to the first exposure field, the photomask table is synchronously moved to The corresponding position of the work piece is exposed at the same time; step 3: judging whether the exposure of all the exposure fields has been completed, and if the judgment result is “No”, the work piece table is stepped to the next exposure field, and the reticle stage is synchronously moved. Go to the corresponding position of the above work piece table and expose at the same time, return to step 3; if the judgment result is "Yes", the exposure ends. This step one includes placing a reticle, placing the substrate, and achieving full field alignment of the substrate.

Compared with the prior art, the present invention transfers the micro-motion stage of the work piece table in the prior art into the micro-motion structure of the reticle stage, so that the difficulty of the whole unit is reduced. In addition, when the apparatus of the present invention is used, when the workpiece table is coarsely moved to the vicinity of the exposure area, the mask stage containing the micro-motion structure immediately dynamically tracks the position of the workpiece stage, since the high-frequency tracking in a small range is similar to scanning photo-etching. The machine can be exposed at the same time. Therefore, the device and the method do not need to be like the conventional stepping photoetching machine structure, the reticle stage does not move, and the step of the workpiece table must be stable until the specified precision is exposed, so It is said that with the device and the method, the step stabilization time is significantly reduced, the total exposure time is correspondingly reduced, and the yield is correspondingly high.

A stepping photoetching apparatus and a photoetching exposure method according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention should be construed as being not limited to the embodiments described below, and the technical idea of the present invention can be implemented in combination with other conventional techniques or functions and other techniques that are the same as those of the prior art.

In the following description, in order to clearly illustrate the structure and working mode of the present invention, it will be described by means of a plurality of directional words, but should be "front", "back", "left", "right", "outside", "inside" Words such as "outward", "inward", "upper", "lower", and the like are understood to be convenience terms and should not be construed as limiting words. Furthermore, the term "X-axis or X-direction" as used in the following description mainly refers to a coordinate axis or direction parallel to the horizontal direction; the term "Y-axis or Y-direction" mainly refers to a direction parallel to the horizontal direction and perpendicular to the X-axis. The axis or direction; the term "Z-axis or Z-direction" mainly refers to the coordinate axis or direction perpendicular to the X-axis Y-axis; the term "Rx-axis" mainly refers to the direction of rotation about the X-axis; "Ry-axis" The word mainly refers to the direction of rotation about the Y axis; the term "Rz axis" mainly refers to the direction of rotation about the Z axis.

Please refer to FIG. 1. FIG. 1 is a schematic structural view of a stepping photoetching apparatus of the present invention. As shown in FIG. 1, the stepping photoetching apparatus comprises an illumination system 1, a Mask Plate 2, a mask 9 placed on the mask table 2, a projection objective 6, a workpiece table 4 and The substrate 7 placed above the workpiece table 4, as well as the integral frame 5 and the position measuring system 3. In the embodiment of the device, the illumination system 1 is illuminated by mercury lamps, providing i-line or gh line or ghi line exposure to form conventional illumination. The projection objective lens 6 adopts a 1:M (M>1) reduced objective lens. Jiadi uses a 1:5 reduced objective lens. In the present invention, the table 4 is of a coarse motion structure and placed between the entire unit frame 5. The reticle stage 2 is of a micro-motion structure and placed over the entire unit frame 5. The substrate 7 is sequentially stepped to each exposure field by the coarse working table 4, and the mask 9 dynamically tracks the vibration of the workpiece table by the fretting reticle stage 2 when the substrate 7 is stepped to the vicinity of the designated exposure area. Exposure is performed while dynamic tracking. The position information of the workpiece table 4 and the reticle stage 2 is measured by the position measuring system 3.

When the stepping light etching apparatus according to the present invention is in operation, when the workpiece table 4 is coarsely moved to the vicinity of the exposure area, the mask stage 2 including the micro-motion structure immediately dynamically tracks the position of the workpiece table 4, because it is high in a small range. The frequency tracking is similar to the scanning photoetching machine, and can be exposed at the same time. Therefore, the device and the method do not need to be fixed like the conventional stepping photoetching machine structure, and the working table step must be stable to the specified position. Only within the precision can be exposed.

For a detailed structure of the workpiece table 4, please refer to FIG. 2 and FIG. 3, wherein FIG. 2 is a plan view of the workpiece table of the stepping photoetching apparatus, and FIG. 3 is a side view of the workpiece table. The workpiece table 4 is a six-dimensional degree of freedom motion mechanism, that is, the workpiece table can satisfy the movements of six directions of X, Y, Z, Rx, Ry, and Rz. Among them, the horizontal direction adopts the H-frame direct drive structure to control the long stroke motion of the X and Y axes, the Rz axis is designed according to the H-type compatible interface, and the horizontal three-axis measurement is controlled by the interferometer measurement. The cam mechanism 46 is used to realize the motion control of the Z, Rx, and Ry axes in the vertical direction, and is measured by an encoder.

Workpiece table 4 horizontal direction architecture adopts H-type drive scheme including X-drive Direction of movement and direction of Y drive. The X drive direction includes two X-direction guide rails 41. The two motor magnet stators 43 and the guide rail 41 assembly are mounted on the work piece table support frame, and the X motor rotors 402a and 402b are fixedly coupled to the Y-beam guide rails to provide X-direction and Rz-direction movement. The Y-direction drive includes a Y-direction guide rail 45, and the Y-direction motor stator 49 is mounted on the Y-direction guide rail 45, and the rotor is mounted on the exposure stage frame. A reclining linear motor is used in the middle of the cross member of the guide rail 45. The H-shaped slider adopts double-rail air-floating guide, the left guide rail 41 is a flat guide rail, and two vertical air-floating pads A51 (vacuum pre-tightening) are arranged between the horizontal X-motor rotor 402a, and only vertical direction support and guidance are provided, and the level is horizontal. The direction is freedom. The right side rail 41 is a two-dimensional rail, and two vertical air floating cushions A52 (vacuum preloading) are disposed between the horizontal X motor rotor 402b, and the Y direction and the Z direction are constrained. The Y-direction motion slider can adopt U-shaped high-rigidity air-floating slider, and the two air-floating pads on the left and right sides of the Y-direction guide rail 45 are mutually pre-tightened, and the vertical direction adopts a high-stiffness air foot 401 (vacuum pre-tightening). The invention simultaneously provides a second technical solution of the work piece table 4, that is, the right side guide rail adopts a steel guide rail, adopts magnetic pre-tightening, adopts two vertical direction air floating sliders and two Rz lateral air floating cushions A53. A flexible block connection may be employed between the Rz lateral air bearing pad A53 and the Y-direction rail. Two X-direction air floating mats on both sides of the beam Y rail, resisting the impact force of the Y-direction motion and the torque of the Rz, the compressed gas is pre-tightened with each other. The bottom of the fretting frame is designed with high rigidity and air foot 401. The marble table is used as the guiding plane. A total of 12 air floating cushions and one air foot can be used.

The vertical movement mechanism of the workpiece table 4 is in addition to the voice coil motor (Voice Coil) The Motor, VCM) direct drive solution is also driven by a conventional cam mechanism 46.

4 and 5, wherein FIG. 4 is a plan view of the reticle stage of the step-and-step photo-etching apparatus, and FIG. 5 is a side view of the reticle stage. The horizontal micro-motor of the reticle stage 2 is driven by three Lorentz motors, including the Lorentz motor SSZX for providing the X direction, and the Lorentz motors SSY1 and SSY2 for the Y direction. The lower surface of the reticle stage 4 is designed with an air-floating guide and is guided by the marble 26 in a plane. The mask table 2 is mounted with two plane mirrors 22 and 21 in the X and Y directions, and is compatible with the 5 吋 and 6 吋 hoods. The reticle stage 2 has no station switching mechanism, and provides a reticle plate interface. The precision of the upper plate is realized by the micro-motion voice coil motor to achieve the accuracy index and stroke compensation of the three-dimensional degrees of freedom of X, Y and Rz. The mask plate is adsorbed on the platen table 25 by a vacuum, and the platen table 25 is designed with a boss. The vertical direction actuator 23 of the reticle stage 2 employs a reed mechanism: three vertical directional support springs are used to connect the marble 26 and the reticle stage frame, with high vertical stiffness and low horizontal stiffness. There is a flexible hinge between the reed and the marble 26 to uncoupling the coupling of the Rx and Ry directions.

In the embodiment of the device, the position measuring system used is as shown in FIG. 6, the horizontal direction XYRz and the like are measured by a laser interferometer, and the Z direction is measured by a built-in code ruler. In addition to the X-direction plane mirror 22 and the Y-direction plane mirror 21 disposed on the mask stage 2, an X-direction plane mirror 42 and a Y-direction plane mirror 44 are also disposed on the workpiece stage 4. The plane mirror reflects the laser emitted by the laser interferometer for measurement in the horizontal direction XYRz.

The working procedure of the stepping light etching apparatus disclosed by the present invention is that the workpiece stage is sequentially stepped to each exposure field by the coarse movement stage, and the mask stage is borrowed when the workpiece stage steps to the vicinity of the designated exposure area. The vibration of the workpiece table is dynamically tracked by the fretting structure of the reticle stage, and exposure is performed while the dynamic tracking is being performed. As shown in FIG. 7, FIG. 7 is a flow chart of the photoetching exposure method. Before the photoetching exposure is performed, the preparation work before the S1 exposure is first completed, and the preparation work before the exposure specifically includes placing the photomask S11, placing the wafer S12, and achieving full field alignment S13 on the wafer. After the preparation work S1 before the exposure is completed, the first step exposure S2 is entered, specifically including stepping the work piece table to the first exposure field position S21, and then the reticle stage dynamically tracks the change of the small position of the work piece table S22 . At the first step exposure S2, the reticle stage tracks the movement of the workpiece table synchronously, and performs exposure while dynamic tracking. It should be noted that the exposure in S22 does not achieve exposure of a complete pattern, so it is also necessary to perform the exposure step S3. When the step S2 is completed, the exposure S3 is simultaneously completed, and the exposure of a complete pattern is completed by the steps S2 and S3. Then proceed to the next (here, second) step exposure S4, the second step exposure S4 step is exactly the same as the first step exposure S2, including stepping the workpiece stage to the next one (ie the first Two) the exposure field position is S41, and then the reticle stage dynamically tracks the change S42 of the small position of the workpiece stage. After the exposure S5 is completed, it is judged whether or not all the exposure fields are exposed to S6. If the result of the determination is negative, the process proceeds to step S4. If the result of the determination is YES, the photoetching exposure is completed, and the wafer is taken out or the wafer S7 is replaced. A preferred technical solution of the embodiment is that the photomask table only tracks the work. The XY and Rz of the table are designed to further reduce the complexity of the system.

The working piece table and the reticle stage defined by the invention can be synchronously moved while being exposed. The main differences between the coarse moving structure and the micro-motion structure include: First, the XY direction of the former is relatively large, for example, both are larger than 30 mm. The latter's stroke is relatively small, such as less than 30mm; second, the former's positioning accuracy (projected on the wafer surface or on the wafer surface) is generally lower than the latter.

The difference between the device of the present invention and the conventional stepper photoetching machine is that the reticle stage of the conventional photoetching machine does not have a micro-motion structure that is exposed while being dynamically movable, but a simple locking structure or other static structure; In addition, the working piece table of the conventional photoetching machine generally includes a coarse moving table and a micro-motion table (or an XY table and a rotating table, and only a few are coarse structures with only H-type).

Moreover, a significant difference between the method of the present invention and a conventional stepper is that the present invention simultaneously tracks the movement of the workpiece table while the exposure is being performed. The reticle stage of the conventional stepper photoetching machine does not track the movement of the workpiece table.

Because the working piece table of the present invention has only a coarse moving structure, the working piece table solution of the present invention is simpler than the coarse moving table plus micro-motion table structure (or XY stage plus Rz stage) adopted by the conventional working piece table; meanwhile, since the objective lens is 1: 5 reduced objective lens, so the yoke table level XY error ratio is relaxed by 5 times in the precision of the workpiece table, and the vertical Z direction positioning error is relaxed to 25 times, so the mask table and the workpiece in the device The system consisting of a table is simpler than the conventional work piece table with a coarse motion + micro-motion structure and a fixed structure when the reticle stage is exposed. That is to say, this scheme transfers the micro-motion stage of the working piece table of the conventional stepping photoetching machine to On the reticle stage, the difficulty of the entire unit was greatly reduced.

When the device of the present invention is used, it can be different from the conventional stepper photoetching machine, that is, when the workpiece table is coarsely moved to the exposure area, the mask table dynamically tracks the position of the workpiece table by the micro-motion structure, and does not require the working piece. The position of the stage is completely stable and can be exposed, so that the total exposure time of the whole wafer is reduced, and the yield is high.

The above description of the present invention is only a preferred embodiment of the present invention, and the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the present invention. Any technical solution that can be obtained by a person skilled in the art according to the idea of the present invention by logic analysis, reasoning or limited experimentation should be within the scope of the present invention.

1‧‧‧Lighting system

2‧‧‧mask table

3‧‧‧Location Measurement System

4‧‧‧Workpieces

5‧‧‧Frame

6‧‧‧Projection objective

7‧‧‧Base

9‧‧‧Photomask

21‧‧‧planar mirror

22‧‧‧planar mirror

23‧‧‧Vertical actuator

25‧‧‧Staining table

26‧‧‧ marble

41‧‧‧rails

42‧‧‧planar mirror

43‧‧‧Motor magnet stator

44‧‧‧planar mirror

45‧‧‧rails

46‧‧‧Cam mechanism

49‧‧‧Y-motor stator

401‧‧‧ Air foot

402a‧‧‧X motor rotor

420b‧‧‧X motor rotor

A51‧‧‧Air cushion

A52‧‧‧Air cushion

A53‧‧‧ air floating cushion

SSY1‧‧ Lorentz motor

SSY2‧‧ Lorentz motor

SSZX‧‧ Lorentz motor

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

1 is a schematic structural view of a step-light etching apparatus of the present invention; FIG. 2 is a plan view of a workpiece stage of a step-light etching apparatus; FIG. 3 is a side view of a workpiece stage of a step-light etching apparatus; FIG. 5 is a side view of a photomask table of a stepping photoetching apparatus; FIG. 6 is a schematic structural view of a position measuring system of a stepping photoetching apparatus; FIG. 7 is a photoetching exposure Flow chart of the method.

1‧‧‧Lighting system

2‧‧‧mask table

3‧‧‧Location Measurement System

4‧‧‧Workpieces

5‧‧‧Frame

6‧‧‧Projection objective

7‧‧‧Base

9‧‧‧Photomask

Claims (10)

A stepping photoetching apparatus comprising: an illumination unit for providing an exposure beam; and a workpiece stage for supporting a substrate to perform six-dimensional degrees of freedom of X, Y, Z, Rx, Ry, and Rz over a large stroke range Movement; a reticle stage for supporting a reticle for X, Y, Z, Rx, Ry, Rz six-dimensional degrees of freedom motion; a projection objective for projecting the reticle pattern onto the substrate at a predetermined ratio; Wherein, after the working piece table is stepped to the exposure field, the reticle stage moves synchronously with respect to the working piece table in a small stroke range and simultaneously exposes. The stepper photoetching apparatus of claim 1, wherein the projection objective has a projection magnification of 1:5. The stepper photoetching apparatus of claim 1, wherein the stepping photoetching apparatus further comprises a position measuring system for performing position measurement and motion control on the workpiece table and the mask table, respectively. The stepper photoetching apparatus of claim 1, wherein the workpiece stage comprises only a coarse motion structure, and the mask stage comprises a micro-motion structure. The stepper photoetching apparatus of claim 4, wherein the horizontal moving device of the working piece table is an H-shaped structure, and the vertical moving device is a voice coil motor or a cam mechanism. A stepper photoetching apparatus according to item 4 of the patent application, wherein the above The horizontal movement device of the reticle stage is a Lorentz motor, and the vertical direction movement device is a reed mechanism. The stepper photoetching apparatus of claim 3, wherein the position measuring system uses a laser interferometer or a coder. The stepping photo-etching apparatus of claim 1, wherein, after the step of the working piece is stepped to an exposure field, the reticle stage moves synchronously with respect to the working piece stage to the working piece table in a small stroke range The X, Y, and Rz positions. A photoetching exposure method using a stepping photo-etching apparatus according to any one of claims 1 to 8, wherein the method comprises: step one, performing pre-exposure preparation work; step two, stepping the work piece to the first step After the exposure field, the reticle stage is synchronously moved to the corresponding position of the workpiece table and exposed at the same time; step 3, judging whether the exposure of all the exposure fields has been completed, and if the determination result is “No”, the workpiece table is stepped to After the next exposure field, the reticle stage is synchronously moved to the corresponding position of the workpiece table and simultaneously exposed, and returns to step 3; if the result of the determination is YES, the exposure ends. The photoetching exposure method of claim 9, wherein the step 1 comprises placing a photomask, placing the substrate, and achieving full field alignment on the substrate.