CN112965344A

CN112965344A - Photoetching system and exposure compensation method thereof

Info

Publication number: CN112965344A
Application number: CN202110184385.1A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shanghai Duning Technology Co ltd
Current assignee: Shanghai Duning Technology Co ltd
Priority date: 2021-02-08
Filing date: 2021-02-08
Publication date: 2021-06-15

Abstract

The invention relates to a photoetching system and an exposure compensation method thereof, wherein the photoetching system comprises a light source, an illuminating mechanism, a workpiece table mechanism, a mask table mechanism, a projection objective, a focusing and leveling mechanism, an alignment mechanism and the like. The workpiece table mechanism is provided with a first movement mechanism and a second movement mechanism connected with the first movement mechanism, the bearing platform is arranged on the second movement mechanism, and the second movement mechanism can move relative to the first movement mechanism so as to realize that the position of the second movement mechanism relative to the first movement mechanism can be adjusted; the mask table mechanism is connected with the first motion mechanism with the coarse motion function, and the second motion mechanism is also connected with the first motion mechanism, so that the second motion mechanism can compensate the alignment deviation of the silicon wafer exposure area in real time according to the position information of the first motion mechanism, the graphic position information of the mask plate and the position information of the silicon wafer actual alignment mark during scanning exposure of the lithography system, and the alignment precision of the lithography system is improved.

Description

Photoetching system and exposure compensation method thereof

Technical Field

The invention relates to the field of photoetching, in particular to a photoetching system and an exposure compensation method thereof.

Background

Photolithography, which is a pattern transfer technique for transferring a pattern on a mask onto a silicon wafer coated with a photoresist, removes a specific portion of a thin film on the surface of the silicon wafer through a series of production steps, is widely used in the manufacture of Integrated Circuits (ICs) and their packages, Flat Panel Displays (FPDs), LED lighting, Micro Electro Mechanical Systems (MEMS), and other precision devices. A lithographic apparatus in lithography is a tool that performs a desired pattern transfer onto a target area of a substrate or silicon wafer. The lithographic apparatus has a contact, proximity, 1:1 projection type and micro projection type, but any of the above-mentioned lithographic apparatus employing any of these modes requires the use of a reticle.

At present, in order to balance the yield, the resolution and the manufacturing cost, 1:1 projection lithography apparatuses are widely used in the fields of advanced packaging, LEDs and the like, and the 1:1 projection lithography apparatuses have two structural forms as follows:

the first is a lithographic apparatus like a miniature projection, which has a lens magnification of 1:1, the mask platform and the workbench move independently, the exposure of the silicon chip or the substrate is realized by a stepping or scanning mode, most of exposure fields do not need to be spliced, and the mask in the photoetching equipment can be larger than the size of the silicon chip or smaller than the size of the silicon chip.

The second type is a photoetching device adopting a 1:1 projection objective lens with a smaller lens field area, wherein a mask plate and a silicon wafer are fixed on the same moving platform, the mask plate and the silicon wafer are kept relatively static in the exposure process, the moving platform carries the mask plate and the silicon wafer to pass through the lens in a reciprocating manner according to a certain track to carry out stepping and scanning movement, so that the exposure of the silicon wafer is completed, and the size of the mask plate of the photoetching device is larger than or equal to that of the silicon wafer.

However, the lithographic apparatus of the above two configurations have the following problems:

first 1:1, because each exposure field of the lithography equipment does not need to be spliced, the area of a single exposure field is large, the cost of a lens is high, and the use cost of the equipment is increased.

(II) second type 1:1 the cost of the motion platform and the lens of the photoetching equipment can be greatly reduced, but the exposure graph of the silicon wafer is often spliced, and because the silicon wafer has harmomegathus, translation and rotation in the manufacturing process, the photoetching machine is in a relatively static state with the mask in the exposure process, the harmomegathus, translation and rotation of the silicon wafer can not be effectively compensated, so that the alignment precision is 1:1 projection lithography machines are poor and thus have a disadvantage in competition for mass production, and cannot be widely applied in the fields of IC advanced packaging, LEDs, MEMS, flat panel display, and the like.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a lithography system and an exposure compensation method thereof, which solve one or more problems of the prior art.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an exposure compensation method of a lithography system, comprising the steps of:

acquiring the actual marking position of the silicon wafer;

calculating silicon wafer deviation according to the actual marking position of the silicon wafer;

dividing the silicon wafer into a plurality of grids, and calculating the offset of the actual graphic position of the silicon wafer in each grid relative to the theoretical graphic position of the silicon wafer according to the silicon wafer deviation;

and the workpiece table mechanism moves along the scanning track and compensates the exposure position of each grid passing through the scanning track according to the offset, so that the actual marking position of the silicon wafer is consistent with the theoretical marking position of the silicon wafer.

Further, the scanning track comprises a scanning starting point, a scanning end point and at least one scanning stopping position arranged between the scanning starting point and the scanning end point.

Further, if the workpiece table does not realize the complete exposure of the silicon wafer when reaching the scanning stop position along the scanning track, the workpiece table continues to move along the scanning track until the complete exposure of the area of the silicon wafer to be exposed is completed.

Further, focusing and leveling are carried out on the silicon chip before the actual marking position of the silicon chip is obtained.

The photoetching system for carrying out exposure compensation by utilizing the exposure compensation method comprises a light source, an illuminating mechanism, a workpiece stage mechanism, a mask stage mechanism, a projection objective and an alignment mechanism, wherein:

the light source is used for emitting exposure light beams;

the illumination mechanism is close to the light source and used for receiving the exposure light beam and realizing exposure illumination;

the workpiece table mechanism is provided with a first motion mechanism and a second motion mechanism connected with the first motion mechanism, a bearing platform used for mounting the silicon wafer is arranged on the second motion mechanism, and the second motion mechanism can perform translational and rotational motion relative to the first motion mechanism so as to realize that the position of the second motion mechanism relative to the first motion mechanism is adjustable;

the mask table mechanism is used for supporting and adsorbing a mask plate with a mask pattern, and is connected with the first motion mechanism so as to realize that the mask table mechanism is driven by the first motion mechanism to move together;

the projection objective is arranged between the mask stage mechanism and the second movement mechanism and is used for projecting the mask pattern to a silicon wafer;

the alignment mechanism is connected with the projection objective and is used for measuring mask pattern marks and silicon wafer marks so as to establish a coordinate relation between the silicon wafer and the mask pattern;

the mask stage mechanism and the first motion mechanism are driven by the first motion mechanism to perform scanning motion, and the second motion mechanism performs scanning motion along with the first motion mechanism and simultaneously adjusts the relative position of the second motion mechanism and the first motion mechanism so as to compensate the deviation between the actual pattern position of the silicon wafer and the theoretical pattern position of the silicon wafer in real time.

Further, the mask stage mechanism may be fixed relative to the first motion mechanism or the mask stage mechanism may be axially displaceable relative to the first motion mechanism.

Further, when the mask stage mechanism can axially displace relative to the first movement mechanism, the mask stage mechanism comprises a first axial movement mechanism and a second axial movement mechanism, a fixed end of the second axial movement mechanism is connected with a movable end of the first axial movement mechanism, and the mask pattern is arranged at the movable end of the second axial movement mechanism, so that the position of the mask plate with the mask pattern can be adjusted.

Furthermore, the mask table mechanism further comprises a first vertical movement module, and the movement end of the first vertical movement module is connected with the fixed end of the first axial movement mechanism.

Furthermore, the first motion mechanism comprises a pair of third axial motion mechanisms and a pair of fourth axial motion mechanisms, wherein the movable end of each third axial motion mechanism is connected with the fixed end of each fourth axial motion mechanism, and the movable end of each fourth axial motion mechanism is connected with the second motion mechanism.

Furthermore, the second motion mechanism comprises a fifth axial motion mechanism and a sixth axial motion mechanism, the fifth axial motion mechanism is provided with a movable end which is connected with the fixed end of the sixth axial motion mechanism, and the sixth axial motion mechanism is provided with a movable end which can move relative to the fifth axial motion mechanism.

Furthermore, the lithography system also comprises a second vertical motion module, wherein the second vertical motion module is arranged between the bearing platform and the movable end of the sixth axial motion mechanism, the second vertical motion module is provided with a fixed end connected with the movable end of the sixth axial motion mechanism, and the second vertical motion module is provided with a movable end used for connecting the bearing platform.

Further, the lithography system further comprises at least one measuring mechanism, wherein the measuring mechanism is close to the second motion mechanism and is used for measuring the displacement of the second motion mechanism relative to the first motion mechanism.

Furthermore, the photoetching system also comprises a focusing and leveling mechanism, wherein the focusing and leveling mechanism is connected with the projection objective lens and is used for measuring the appearance of the upper surface of the silicon chip and the distance between the upper surface of the silicon chip and the optimal focal plane of the objective lens, and establishing the relation between the upper surface of the silicon chip and the optimal focal plane of the objective lens.

Compared with the prior art, the invention has the following beneficial technical effects:

the mask table mechanism is connected with the first motion mechanism with the coarse motion function, and the second motion mechanism is connected with the first motion mechanism, so that compared with the traditional mask table mechanism which is relatively static with the position of the silicon wafer, the mask table mechanism can compensate the overlay deviation of the silicon wafer exposure area in real time according to the position information of the first motion mechanism, the graphic position information of the mask plate and the actual alignment mark position information of the silicon wafer during scanning exposure, so that the overlay accuracy of a photoetching system is improved.

Furthermore, the photoetching system is additionally provided with a first axial motion mechanism, a second axial motion mechanism and a first vertical motion module in the mask table mechanism, so that the mask with the mask pattern can be subjected to plate loading and plate unloading. If the mask plate has high precision or the second motion mechanism can compensate the precision loss of the mask plate, the structures of the first axial motion mechanism, the second axial motion mechanism and the first vertical motion module in the mask table mechanism can be simplified, and the system cost is further reduced.

And thirdly, the photoetching system is additionally provided with a first axial motion mechanism, a second axial motion mechanism and a first vertical motion module in the mask table mechanism, so that the mask plate with the mask pattern can realize plate loading and plate unloading, and the first axial motion mechanism and the second axial motion mechanism of the mask table mechanism can also compensate the overlay deviation of the silicon wafer exposure area in real time according to the position information of the first motion mechanism of the workpiece table mechanism, the pattern position information of the mask plate and the actual alignment mark position information of the silicon wafer, thereby improving the overlay precision of the photoetching system. Therefore, the second movement mechanism of the workpiece table mechanism can be simplified, and the system cost is further reduced.

And (IV) further, the photoetching system has the advantages of low cost, high yield and high precision.

Drawings

FIG. 1 is a schematic diagram of a lithography system and a method for compensating exposure thereof according to an embodiment of the present invention.

FIG. 2 is a front view of a first motion mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the invention.

FIG. 3 is a top view of a first motion mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the invention.

FIG. 4 is a front view of a second motion mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the invention.

FIG. 5 is a top view of a second motion mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the invention.

FIG. 6 is a schematic diagram illustrating a connection between the support platform and the second vertical motion module in the lithography system and the exposure compensation method thereof according to the embodiment of the invention.

FIG. 7 depicts a top view of a mask table mechanism in a lithography system and exposure compensation method thereof according to an embodiment of the invention.

FIG. 8 is a front view of a mask table mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of an arrangement of a measurement mechanism in a lithography system and an exposure compensation method thereof according to an embodiment of the invention.

FIG. 10 is a flowchart illustrating an exposure compensation method of a lithography system according to an embodiment of the invention.

FIG. 11 is a schematic diagram showing the deviation between the actual alignment mark and the theoretical alignment mark of the silicon wafer during the exposure process of the lithography system according to the embodiment of the present invention.

FIG. 12 is a schematic diagram of an overlay deviation compensation grid during exposure of a lithography system according to an embodiment of the present invention.

FIG. 13 is a schematic view of the lens exposure field during exposure of the lithography system according to an embodiment of the present invention.

FIG. 14 is a schematic diagram of a scanning track during exposure of a lithography system according to an embodiment of the present invention.

FIG. 15 is a schematic diagram showing a scanning track of a trapezoidal light spot during exposure of a lithography system according to another embodiment of the present invention.

FIG. 16 is a view showing an exposure field in which an exposure spot is trapezoidal during exposure in a lithography system according to another embodiment of the present invention.

FIG. 17 is a schematic diagram showing the scanning track of a triangular light spot during exposure of a lithography system according to another embodiment of the present invention.

FIG. 18 is a view of the exposure field showing triangular exposure spots during exposure in a lithography system according to another embodiment of the present invention.

In the drawings, the reference numbers: 1. a light source; 2. an illumination mechanism; 3. a frame; 4. a mask stage mechanism; 40. a rotating bearing; 41. a first base; 42. a first axial movement mechanism; 420. a first motor; 4201. a first stator; 4202. a first mover; 421. a first guide rail; 422. a first slider; 423. a first moving plate; 43. a second axial movement mechanism; 431. a second slider; 432. a second guide rail; 433. a second motor; 4331. a second stator; 4332. a second mover; 44. a plate bearing boss; 45. masking the plate; 46. a plate bearing table; 47. a first vertical motion module; 471. a servo motor; 472. a roller; 473. a cam; 481. an air floating cushion mounting seat; 482. an air-bearing cushion; 483. a vacuum adsorption zone; 49. a vertical module mounting base; 5. a projection objective; 6. an alignment mechanism; 7. a focusing and leveling mechanism; 8. a transport mechanism; 91. a first measuring mechanism; 92. a second measuring mechanism; 10. a shock absorber; 11. a first movement mechanism; 1101. a third guide rail; 1102. a second base; 1103. pneumatically supporting; 1104. a third motor; 11041. a third stator; 11042. a third mover; 1105. a third slider; 1106. a connecting plate; 1107. a first support frame; 1108. a micro-motion bracket; 1109. a first pneumatic cushion; 1110. a second pneumatic cushion; 1111. a third pneumatic cushion; 1112. a fourth motor; 11121. a fourth stator; 11122. a fourth mover; 12. a second movement mechanism; 1200. a fifth motor; 12001. a fifth stator; 12002. a fifth mover; 1201. a second moving plate; 1202. a sixth motor; 12021. a sixth mover; 12022. a sixth stator; 1203. a third moving plate; 13. a third base; 14. a second vertical motion module; 15. a load-bearing platform; 161. a first reflector; 162. a second reflector; 17. an adsorption mechanism.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the photolithography system and the exposure compensation method thereof according to the present invention are described in further detail below with reference to the accompanying drawings and the detailed description. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are all used in a non-precise scale for the purpose of facilitating and distinctly aiding in the description of the embodiments of the present invention. To make the objects, features and advantages of the present invention comprehensible, reference is made to the accompanying drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the implementation conditions of the present invention, so that the present invention has no technical significance, and any structural modification, ratio relationship change or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention.

In the following description, for the purposes of clearly illustrating the structure and operation of the present invention, directional terms will be used, but terms such as "front", "rear", "left", "right", "outer", "inner", "outer", "inward", "upper", "lower", etc. should be construed as words of convenience and should not be construed as limiting terms. Furthermore, the term "X-axis or X-direction" used in the following description mainly refers to a horizontal direction parallel coordinate axis or direction; the term "Y-axis or Y-direction" mainly refers to a coordinate axis or direction parallel to the horizontal direction and perpendicular to the X-axis; the term "Z-axis or Z-direction" mainly refers to a coordinate axis or direction perpendicular to both the X-axis and the Y-axis; the term "Rz axis" refers primarily to the direction of rotation about the Z axis.

The first embodiment is as follows:

referring to fig. 1, fig. 1 is a schematic structural diagram of a lithography system according to the present invention, and as shown in fig. 1, the following first describes a specific structure of the lithography system as follows:

referring to fig. 1, the lithography system includes a light source 1, an illumination mechanism 2, a stage mechanism, a mask stage mechanism 4, a projection objective 5, an alignment mechanism 6, and a focusing and leveling mechanism 7, the light source 1, the illumination mechanism 2, and the projection objective 5 together form an exposure mechanism of the lithography system, the light source 1, the illumination mechanism 2, the projection objective 5, the alignment mechanism 6, and the focusing and leveling mechanism 7 are in a relatively static state during scanning and exposure of the lithography system, the mask stage mechanism 4 (including a mask adsorbed by the mask stage mechanism) is fixed on a first motion mechanism 11 of the stage mechanism and scans and moves along with the first motion mechanism 11, a second motion mechanism 12 of the stage mechanism is disposed on the first motion mechanism 11 and adjusts a relative position between the two motion mechanisms in real time with respect to the first motion mechanism 11 during scanning and exposure of the first motion mechanism 11, the deviation between the actual pattern position of the silicon wafer and the theoretical pattern position of the silicon wafer is compensated in real time (the related error is calculated according to the deviation of the alignment mark position), and specifically, the deviation between the actual pattern position of the silicon wafer and the theoretical pattern position of the silicon wafer is compensated by driving the silicon wafer to move relative to the mask plate through the second movement mechanism 12 of the workpiece table mechanism.

The light source 1 is used for emitting an exposure light beam, in this embodiment, the light source 1 is an exposure light source, specifically, an exposure light beam emitted by an exposure emitter, which can provide i-line, gh-line, ghi-line, KrF or ArF exposure, and the like.

Of course, in other embodiments of the present invention, the light source 1 may be a mercury lamp.

The illumination mechanism 2 is arranged close to the emergent end of the light source 1, the illumination mechanism 2 is fixed on the frame 3, the illumination mechanism 2 is used for collecting the exposure light beam and providing uniform exposure light spots for a mask pattern of the photoetching machine, the exposure light spots are an energy source of the projection photoetching machine, the light spot energy on the surface of the mask pattern and the illumination uniformity are important indexes of an illumination system, the size of the light spot energy determines the yield of the photoetching machine, and the illumination uniformity determines the relative difference of the directional widths of exposure lines when the projection photoetching machine is exposed. In the embodiment of the present invention, the illumination mechanism 2 is composed of a shutter, a uniform rod and an illumination lens group, and the structure and the working principle thereof all belong to the known technology, which is not described in detail herein.

The workpiece table mechanism is provided with a first movement mechanism 11 and a second movement mechanism 12 connected with the first movement mechanism 11, wherein the first movement mechanism 11 adopts a coarse movement structure and can realize horizontal large-stroke movement, the second movement mechanism 12 adopts a micro-movement structure, a bearing platform 15 used for mounting a silicon wafer is arranged on the second movement mechanism 12, and the second movement mechanism 12 can move relative to the first movement mechanism 11 so as to realize that the position of the second movement mechanism 12 relative to the first movement mechanism 11 is adjustable.

The mask stage mechanism 4 is used for supporting and adsorbing a mask plate with a mask pattern, the mask stage mechanism 4 is connected with the first moving mechanism 11, so that the position of the mask stage mechanism 4 relative to the illuminating mechanism 2 is adjustable, and the mask stage mechanism 4 is fixed on the first moving mechanism 11 and moves together to realize simultaneous exposure in the process of dynamic movement.

The projection objective 5 is fixed on the frame 3, the projection objective 5 is located between the mask stage mechanism 4 and the second movement mechanism 12, and is used for projecting a mask pattern onto a silicon wafer, in the embodiment of the present invention, the projection objective 5 adopts a configuration of 1: projection objective of formula 1.

The alignment mechanism 6 is connected to the projection objective 5 for measuring the mask pattern marks and the silicon wafer marks to establish the coordinate relationship between the silicon wafer and the mask pattern, and in the lithography system according to the embodiment of the present invention, the alignment mechanism 6 employs an alignment sensor.

The focusing and leveling mechanism 7 is connected with the projection objective 5 and used for measuring the appearance of the upper surface of the silicon chip and the distance between the upper surface of the silicon chip and the optimal focal plane of the objective so as to establish the relation between the upper surface of the silicon chip and the optimal focal plane of the objective.

The specific structure of the mask stage mechanism 4 is described first below as follows:

referring to fig. 7 and 8, the mask stage mechanism 4 includes two sets of first axial moving mechanisms 42 and a second axial moving mechanism 43 connected to the first axial moving mechanisms 42, wherein the first axial moving mechanisms 42 are disposed on the upper surface of the first base 41.

With continued reference to fig. 7 and 8, the first axial motion mechanism 42 includes a first motor 420, a first guide rail 421 and a first slider 422, the first motor 420 is a three-phase linear motor and has a first stator 4201 and a first mover 4202, the first mover 4202 is connected to a first moving plate 423, the first moving plate 423 has another portion connected to the first slider 422 through a rotating bearing 40, the first slider 422 is slidably connected to the first guide rail 421, and a magnetic field of the first stator 4201 of the first motor 420 moves the first mover 4202 in the magnetic field and drives the first slider 422 to move relative to the first guide rail 421, so as to complete the translational motion of the first moving plate 423 and the first slider 422 in the Y direction.

Further, the first movers 4202 of the two sets of first axial motion mechanisms 42 adjacent to each other on the left and right are connected to the second axial motion mechanism 43, a rotation bearing 40 is added in the lithography system according to the first embodiment of the present invention, the rotation bearing 40 is connected to the first slider 422 and the first moving plate 423, and the first axial motion mechanisms 42 can realize the Y-direction and Rz-direction motions by decoupling the rotation bearing 40.

With continued reference to fig. 7 and 8, the second axial movement mechanism 43 includes a second motor 433, a second guide rail 432, and a second slider 431, the second motor 433 is a voice coil motor and has a second stator 4331 and a second mover 4332, the second mover 4332 is connected to the second slider 431, the second slider 431 is connected to the second guide rail 432 in a sliding manner, and the plate receiving table 46 is connected to the second slider 431, and similarly, when the second motor 433 is energized, the magnetic field of the second stator 4331 moves the second mover 4332 in the magnetic field and drives the second slider 431 to move relative to the second guide rail 432, thereby implementing the translational movement of the plate receiving table 46 and the second slider 431 in the X direction.

With continued reference to fig. 7 and 8, a plurality of plate bearing bosses 44 are located on the surface of the plate bearing table 46, and the plate bearing bosses 44 jointly adsorb and fix a mask 45 having a mask pattern. In order to ensure the stability of the movement of the plate bearing table 46, an air floating pad 482 is arranged at the bottom of the plate bearing table 46, the air floating pad 482 is mounted on an air floating pad mounting seat 481, and the air floating pad mounting seat 481 is fixed on the first base 41. Meanwhile, a vacuum adsorption area 483 is arranged below the plate bearing table 46, the bottom of the plate bearing table 46 is in translational motion through an air floating pad 482, and when the plate bearing table 46 moves to a target position, the vacuum adsorption area 483 is opened, and the positive pressure of the air floating pad 482 is closed, so that the plate bearing table 46 can be adsorbed and fixed.

With continued reference to fig. 7 and 8, in order to facilitate the upper and lower plate movements of the mask 45, the lithography system is provided with at least three sets of first vertical movement modules 47, each of the first vertical movement modules 47 includes a servo motor 471, a roller 472, and a cam 473, and the servo motor 471 drives the roller 472 to rotate and realize the movement of the inclined surface relative to the cam 473, so as to realize the small-amplitude ascending or descending movement of the first base 41.

Of course, in other embodiments of the present invention, the first vertical movement module 47 may also be implemented by directly driving a voice coil motor having a rotor and a stator, wherein the rotor is connected to the lower surface of the first base 41, the stator generates a vertical moving magnetic field after being energized with an ac current and drives the rotor to move in the vertical direction, and drives the first base 41 and the first axial movement mechanism 42 and the second axial movement mechanism 43 mounted on the surface of the first base 41 to lift together, so as to implement the lifting or lowering action of the mask 45.

The specific structure of the first movement mechanism 11 is described below:

referring to fig. 2 and 3, the first moving mechanism 11 can satisfy long axis movement in the X direction and the Y direction, wherein a "H" type structure direct driving structure is adopted to control X, Y axial long stroke movement in the horizontal direction, the "H" type structure includes two sets of third axial moving mechanisms and fourth axial moving mechanisms, wherein the third axial moving mechanisms are mechanisms moving along the Y direction, and the fourth axial moving mechanisms are mechanisms moving along the X direction.

Specifically, with continuing reference to fig. 2 and fig. 3, the third axial movement mechanism is disposed at the left and right positions of the first support frame 1107 and includes a third motor 1104, the third motor 1104 includes a third stator 11041 and a third rotor 11042, the third rotor 11042 is connected to a third slider 1105 and a first pneumatic floating cushion 1109, the first pneumatic floating cushion 1109 is suspended relative to the third guide rail 1101 by compressed air, so as to achieve smooth movement without friction and vibration, the first pneumatic floating cushion 1109 has a rigid air film, and a gap between the first pneumatic floating cushion 1109 and the third guide rail 1101 is stable and moves without friction. The third motor 1104 is a linear motor and has a linear motor stator, and the third stator 11041 mainly functions to generate a magnetic field. And the third rotor 11042 drives the third slider 1105 to move in translation along the Y direction. The third guide 1101 is mounted on a first support frame 1107. A connecting plate 1106 is connected between two adjacent third sliding blocks 1105, and the fourth axial motion mechanism is installed on the connecting plate 1106.

With continued reference to fig. 2 and fig. 3, the fourth axial motion mechanism includes a fourth motor 1112, wherein the fourth motor 1112 has a fourth stator 11121 and a fourth rotor 11122, the fourth motor 1112 can perform a reciprocating translational motion along the X direction, referring to fig. 4, the fourth rotor 11122 is connected to a micro-motion bracket 1108, the mask stage mechanism 4 is also connected to the micro-motion bracket 1108, the bottom of the micro-motion bracket 1108 is connected to a first support 1107 through a pneumatic support 1103, the first pneumatic support 1103 is disposed on a second base 1102, the second base 1102 is fixed to the first support 1107, and the third guide 1101 is also fixed to the first support 1107.

Further, with continuing reference to fig. 2 and fig. 3, the third axial moving mechanism is distributed on the left and right sides of the fourth axial moving mechanism, wherein the third guideway 1101 of the third axial moving mechanism located on the left side of the fourth axial moving mechanism is configured with two first pneumatic floating cushions 1109 (vacuum pre-tightening), wherein the first pneumatic floating cushions 1109 are vertical pneumatic floating cushions, which only provide vertical support and are free in the horizontal direction. The right third rail 1101 is a two-dimensional rail, and a plurality of second pneumatic pads 1110 and a plurality of first pneumatic pads 1109 are disposed in the right third axial motion mechanism, so that the degrees of freedom in the X direction and the Z direction are restricted.

Further, with continued reference to fig. 2 and 3, a fourth axial moving mechanism has two third pneumatic floating pads 1111 at two sides of the guide rail, the third pneumatic floating pads 1111 are Y-directional floating pads, and have impact force resisting the Y-directional movement and torque resisting the Rz-directional movement, and the compressed air is pre-tensioned each other.

The specific structure of the second movement mechanism 12 is described below as follows:

referring to fig. 4 and 5, the second moving mechanism 12 includes at least one fifth axial moving mechanism and at least one sixth axial moving mechanism, the fifth axial moving mechanism is used for implementing a linear movement in the X direction, and the sixth axial moving mechanism implements a linear movement in the Y direction. In the lithography system according to the embodiment of the invention, two fifth axial motion mechanisms and two sixth axial motion mechanisms are respectively arranged.

Wherein the fifth axial motion mechanism and the sixth axial motion mechanism are arranged perpendicular to each other, wherein the fifth axial motion mechanism realizes a translational motion in the Y direction, and the sixth axial motion mechanism realizes a translational motion in the X direction. With continued reference to fig. 4 and fig. 5, the fifth axial motion mechanism includes a fifth motor 1200, the fifth motor 1200 includes a fifth stator 12001 and a fifth mover 12002, the fifth stator 12001 is connected to the second moving plate 1201, and when the fifth motor 1200 is powered on, the fifth stator 12001 causes the fifth mover 12002 to drive the third moving plate 1203 to slightly move along the Y direction through a magnetic field. The sixth motor 1202 is mounted on the second moving plate 1201, the sixth motor 1202 has a sixth stator 12021 and a sixth stator 12022, the sixth stator 12022 is coupled to the second moving plate 1201, the sixth stator 12021 is coupled to the third moving plate 1203, and when the sixth motor 1202 is energized, the sixth stator 12022 causes the sixth rotor 12021 to drive the third moving plate 1203 to slightly move in the X direction by a magnetic field.

Referring to fig. 3 and 5, the photolithography system further includes a second vertical motion module 14, the second vertical motion module 14 is mounted on the third moving plate 1203, and the second vertical motion module 14 is driven by a voice coil motor directly to move vertically. The second vertical motion modules 14 are provided with stators and rotors, the second vertical motion modules 14 are uniformly distributed at the bottom of the bearing platform 15 in three equal parts, the rotor end of each second vertical motion module 14 is connected with the bearing platform 15, the bearing platform 15 is provided with an adsorption mechanism 17 for adsorbing a silicon wafer, the adsorption mechanism 17 can be a suction cup, and the suction cup is connected with a vacuum device through a pipeline, so that the suction cup has adsorption force and can adsorb the silicon wafer.

Of course, in other embodiments of the present invention, three or more second vertical motion modules 14 may be provided, and they may also be non-uniformly distributed, and the second vertical motion modules 14 may also adopt the same structure as the first vertical motion modules 47 to implement the ascending and descending actions, such as a cam form, which only needs to be satisfied that the carrying platform 15 can ascend or descend.

Referring to fig. 1 and 9, the lithography system further includes at least one measuring mechanism, which is close to the second moving mechanism 12 and fixed on the frame 3 or the first moving mechanism 11, for measuring a moving position of the second moving mechanism 12 relative to the first moving mechanism. In the lithography system according to the embodiment of the invention, the measuring mechanism includes a first measuring mechanism 91 and a second measuring mechanism 92, wherein the first measuring mechanism 91 is used for measuring the moving position of the second moving mechanism 12 along the Y direction, the second measuring mechanism 92 is used for measuring the moving position of the second moving mechanism 12 along the X direction, and both the first measuring mechanism 91 and the second measuring mechanism 92 adopt a laser interferometer or a laser ruler. Accordingly, the measurement can be made by an encoder when the Z-direction needs to be measured.

In order to facilitate the above-mentioned exposure interferometer to receive the measurement signal, a first reflecting mirror 161 and a second reflecting mirror 162 are respectively disposed on the supporting platform 15, wherein the first reflecting mirror 161 is used for feeding back the measurement signal to the second measuring mechanism 92, and the second reflecting mirror 162 is used for feeding back the measurement signal to the first measuring mechanism 91, so as to respectively calculate the displacement of the first measuring mechanism 91 and the second measuring mechanism 92.

Referring to fig. 1 and 4, in order to eliminate the focal plane error of the silicon wafer on the vertical surface, the lithography system further includes a focusing and leveling mechanism 7, where the focusing and leveling mechanism specifically uses a focusing and leveling sensor, and measures the surface of the silicon wafer by using the focusing and leveling sensor, and if the surface of the silicon wafer is not flat, the focusing and leveling mechanism controls part of the second vertical motion modules 14 or all the movers of the second vertical motion modules 14 to ascend or descend so as to realize the ascending or descending of the whole bearing platform 15, and the second vertical motion modules 14 stop working until the focusing and leveling sensor detects that the focal plane error on the vertical surface of the silicon wafer is eliminated, so as to ensure that the exposure area of the silicon wafer is at the optimal focal plane.

With reference to fig. 1, the frame 3 is integrally disposed on a vibration isolation foundation, the vibration isolation foundation includes at least one damper 10 and a third base 13 connected to the damper 10, the third base 13 is further disposed with a transmission mechanism 8, and the transmission mechanism 8 may adopt a structure such as a three-axis linear module, so as to place or take out a silicon wafer on the bearing platform 15 and place or take out a mask 45 on the bearing platform 44.

The following describes a method for performing exposure compensation by using the above lithography system, comprising the steps of:

s1: and (3) masking: referring to fig. 1, after the first motor 420 of the first axial motion mechanism 42 is started, the first mover 4202 drives the first slider 422 to move to a designated position along the Y-direction relative to the first guide rail 421, and then the second motor 433 of the second axial motion mechanism 43 is started, and moves to a designated position along the X-direction relative to the second guide rail 432 through the second mover 4332. The first vertical movement module 47 is started, the servo motor 471 of the first vertical movement module 47 is started, the servo motor drives the roller 472 to rotate and realizes the rotation of the cam 473 to realize that the first base 41 moves to the upper mask plate station along the Z direction, the transmission mechanism 8 transmits the mask plate 45 to the bearing plate boss 44, the mask plate 45 is adsorbed on the bearing plate boss 44 through vacuum, then the first vertical movement module 47 moves to enable the mask plate 45 to move to the exposure vertical station, and then the first axial movement mechanism 42 and the second axial movement mechanism 43 move the mask plate 45 to the exposure horizontal station.

S2: and (3) silicon chip loading: referring to fig. 1, fig. 2 and fig. 3, specifically, the third stator 11041 in the third motor 1104 generates a magnetic field, the third rotor 11042 moves to a designated position along the Y direction, and then the fourth motor 1112 is started, the fourth rotor 11122 drives the micro-motion support 1108 to translate to the designated position along the X direction, and the transmission mechanism 8 places the silicon wafer above the supporting platform 15 and adsorbs the silicon wafer through the adsorption mechanism 17.

S3: silicon chip full-field focusing and leveling: and measuring the upper surface of the silicon wafer through the focusing and leveling sensor to obtain horizontal information data and surface information data of the silicon wafer and enable the silicon wafer to enter a focal depth range. When the silicon wafer needs to be adjusted, the second vertical motion module 14 or the movers of all the second vertical motion modules 14 are controlled to ascend or descend so as to realize the integral ascending or descending of the bearing platform 15, and the second vertical motion module 14 stops working after the focusing and leveling sensor detects that the focal plane error on the vertical surface of the silicon wafer is eliminated so as to ensure that the exposure area of the silicon wafer is in the optimal focal plane position.

S4: full-field alignment of silicon wafers: the marks on the surface of the mask 45 and the marks on the surface of the silicon wafer are measured separately or simultaneously by the alignment sensor to establish a coordinate relationship between the silicon wafer and the mask pattern on the mask 45.

S5: calculating the silicon wafer expansion and contraction or translation or rotation deviation, namely the offset:

referring to fig. 11, alignment measurement is performed on the mark on the silicon wafer, where a1 is the actual mark position and B1 is the theoretical mark position in fig. 11, and the deviations Δ xi and Δ yi of the actual mark position a1 from the theoretical mark position B1 satisfy a six-parameter model:

wherein: xi and yi are respectively position coordinates of the actual mark of the silicon wafer; tx and Ty are respectively silicon wafer translation, namely offset; mx and My are multiplying power;

rotating the image plane; rxi and Ryi are fitting residuals respectively.

Six parameters Tx, Ty, Mx and My can be obtained by fitting by adopting a least square method,

of course, in other embodiments of the present invention, other methods may be usedThe invention is not limited to the calculation method.

S6: the photoetching system divides a silicon wafer into a plurality of grids which are arranged in a matrix mode along the transverse direction and the longitudinal direction through photoetching software according to the requirement of overlay accuracy (the grid width in the non-scanning direction is matched with the width of an exposure field as much as possible), the area of the silicon wafer is covered by a rectangular area formed by enclosing a plurality of grids so as to realize scanning exposure of the whole area of the silicon wafer, the offset of the silicon wafer in each grid relative to a mask is calculated through the software, and the grids can be divided into equal parts or unequal parts.

Assuming that the nominal position of the center of the grid to be exposed is (xc0, yc0), the compensated desired position of the center of the grid (xci, yci) satisfies:

particularly, when the grid in the scanning direction is infinitely small, the lithography system can realize real-time continuous compensation of errors in the scanning direction, namely real-time compensation of errors at any exposure position. Assuming that the nominal position of the center of the virtual exposure visual field is (xc0, yc0), the compensated actual exposure visual field center expected position (xci, yci) satisfies:

s7: referring to fig. 1 and 12, the first motion mechanism 11 drives the mask stage mechanism 4 to move to the start position of the scanning exposure, specifically, after the third stator 11041 in the third motor 1104 moves the third rotor 11042 to the designated position along the Y direction through the magnetic field, the fourth motor 1112 is started, the fourth rotor 11122 drives the fine motion bracket 1108 to translate to the designated position along the X direction, the fourth rotor 11122 is connected to the fine motion bracket 1108, and the vertical module mounting seat 49 of the mask stage mechanism 4 is connected to the fine motion bracket 1108, because the second motion mechanism 12 is also connected to the fine motion bracket 1108, the motion of the fourth rotor 11122 can drive the fine motion bracket 1108, the mask stage mechanism 4, and the second motion mechanism 12 to move integrally.

S8: referring to fig. 10, 12, 13 and 14, the illumination mechanism 2 collects the exposure beam and forms an exposure spot on the lens exposure field after passing through the mask pattern of the reticle and the objective lens, and referring to fig. 13, a hexagonal exposure spot is formed on the lens exposure field in the first embodiment of the present invention. The first motion mechanism 11 drives the mask stage mechanism 4 and the second motion mechanism 12 to scan along the scanning track from the scanning start position, the second motion mechanism 12 performs real-time compensation by driving the micro-motion motor to move according to the deviation of the exposure position, wherein the compensation in the X direction is performed by driving the sixth motor 1202 to make the sixth stator 12022 generate a magnetic field and making the sixth rotor 12021 drive the third moving plate 1203 to slightly move in the X direction, the compensation in the Y direction is performed by driving the fifth stator 12002 to generate a magnetic field and making the fifth rotor 12001 drive the third moving plate 1203 to move, and the compensation for Rz is performed by the differential motion of the fifth motor 1200 or the sixth motor 1202.

In the process of scanning and exposing along the scanning track, the mask stage mechanism 4 can also realize the small-range real-time adjustment of the relative position of the mask plate 45 with the mask pattern relative to the first movement mechanism 11 through the translational movement of the first axial movement mechanism 42 and the second axial movement mechanism 43, and compensate the deviation of the actual pattern position of the silicon wafer and the theoretical position of the silicon wafer in real time through the movement of the mask plate 45 (calculating the related error according to the deviation of the alignment mark position), so that the alignment precision of the lithography system is improved. Certainly, in the lithography system of the first embodiment, the second motion mechanism 12 can adjust the position in real time in a small range relative to the first motion mechanism 11 in the scanning exposure process of the first motion mechanism 11, so as to further compensate the deviation between the actual pattern position of the silicon wafer and the theoretical pattern position of the silicon wafer in real time, and further improve the overlay accuracy of the lithography system accurately. In the first embodiment, the position is adjusted in real time by the movement of the reticle 45 relative to the first movement mechanism 11 and the movement of the second movement mechanism 12 relative to the first movement mechanism 11.

Of course, in other embodiments of the present invention, the shape of the exposure spot formed on the exposure field of the lens may be different, for example, it may be trapezoidal as shown in fig. 16, or it may be triangular as shown in fig. 18, or it may be rhombus or any other shape besides the above shapes. When the profile of the exposure spot is a trapezoid as shown in fig. 16, please refer to fig. 15, the scanning track is the same as the scanning track of the first embodiment of the present invention; when the profile of the exposure spot is triangular as shown in fig. 18, please refer to fig. 17, after the scanning track moves to the last line of grids, it needs to go another scanning track in the opposite direction outside the last line of grids, so that all the exposure fields are exposed.

S9: referring to fig. 10, 12 and 14, the first moving mechanism 11 moves to the next scanning start position, referring to fig. 12, that is, the first moving mechanism 11 stops at the next scanning start position before the grid of the last row enters the grid of the last row along the scanning track, the first moving mechanism 11 drives the mask stage mechanism 4 and the second moving mechanism 12 to scan along the scanning track from the scanning start position, and the second moving mechanism 12 performs real-time compensation according to the deviation of the exposure position.

S10: and judging whether the silicon wafer is completely exposed, if not, returning to the step S9, and continuing to perform scanning exposure along the scanning track from the next scanning starting position by the first motion mechanism 11 until all the exposure fields needing to be exposed are exposed.

S11: the silicon wafer is taken out and replaced by the transfer mechanism 8, and the loop from the step S1 to the step S11 is continued. If the reticle is not to be replaced, the process loops from the step S2 to the step S11.

Example two:

the second embodiment of the lithography system is largely the same as the first embodiment of the lithography system in structure and operation, except that the mask stage mechanism 4 is fixed relative to the first movement mechanism in the lithography system, and the mask stage mechanism 4 does not have the first axial movement mechanism 42 and the second axial movement mechanism 43 in the second embodiment of the lithography system, so that the position of the mask blank with the mask pattern is not adjustable relative to the first movement mechanism 11 and the second movement mechanism 12. However, the mask stage mechanism 4 is always connected to the first motion mechanism 11 and can perform a large-range scanning motion along with the first motion mechanism 11, and the second motion mechanism 12 adjusts the position in real time in a small range relative to the first motion mechanism 11 in the scanning exposure process of the first motion mechanism 11, so as to further compensate the deviation between the actual pattern position of the silicon wafer and the theoretical pattern position of the silicon wafer in real time, and further improve the alignment precision of the lithography system accurately.

Example three:

third embodiment the lithography system is largely the same as the first embodiment, except that the second moving mechanism 12 can simplify the fifth axial moving mechanism for realizing the linear movement in the X direction and the sixth axial moving mechanism for realizing the linear movement in the Y direction in the structure of the lithography system, and the second motion mechanism 12 and the first motion mechanism 11 are relatively fixed, the mask table mechanism 4 realizes the small-range real-time adjustment of the relative position of the mask plate 45 with the mask pattern relative to the first motion mechanism 11 through the translational motion of the first axial motion mechanism 42 and the second axial motion mechanism 43, the deviation between the actual graph position of the silicon chip and the theoretical position of the silicon chip is compensated in real time by the movement of the mask 45 (the related error is calculated according to the deviation of the alignment mark position), thereby improving the alignment precision of the photoetching system, in the third embodiment, the position adjustment relative to the first movement mechanism 11 is achieved only by the movement of the reticle 45.

The lithography system according to the third embodiment also has at least one measurement mechanism, but the measurement mechanism is close to the mask stage mechanism 4 and can be fixed to the frame 3 or fixed to the first motion mechanism 11, and is configured to measure a displacement amount of the mask stage mechanism 4 relative to the first motion mechanism 11.

In addition, for convenience of understanding, the various motion mechanisms related to the embodiments of the present invention are operated one by one according to the description sequence, but the actual working process is not limited to be operated one by one, the motion actions of the various motion mechanisms may be linked, and the present invention is not limited thereto.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An exposure compensation method of a lithography system, comprising the steps of:

acquiring the actual marking position of the silicon wafer;

2. An exposure compensation method of a lithography system as claimed in claim 1, wherein: the scanning track comprises a scanning starting point, a scanning end point and at least one scanning stopping position arranged between the scanning starting point and the scanning end point.

3. An exposure compensation method of a lithography system as claimed in claim 2, wherein: and if the workpiece platform does not realize the complete exposure of the silicon wafer when reaching the scanning stop position along the scanning track, the workpiece platform continues to move along the scanning track until the area of the silicon wafer to be exposed is completely exposed.

4. An exposure compensation method of a lithography system as claimed in claim 1, wherein: and focusing and leveling the silicon wafer before acquiring the actual marking position of the silicon wafer.

5. A lithography system for performing exposure compensation by using the exposure compensation method of claims 1 to 4, characterized in that: the photoetching system comprises a light source, an illuminating mechanism, a workpiece table mechanism, a mask table mechanism, a projection objective and an aligning mechanism, wherein:

the light source is used for emitting exposure light beams;

the mask table mechanism is used for supporting and adsorbing a mask plate with a mask pattern, and is connected with the first motion mechanism so as to realize that the mask table mechanism is driven by the first motion mechanism to move together; the projection objective is arranged between the mask stage mechanism and the second movement mechanism and is used for projecting the mask pattern to a silicon wafer;

6. The lithography system of claim 5, wherein: the mask stage mechanism is fixed relative to the first motion mechanism or the mask stage mechanism is axially displaceable relative to the first motion mechanism.

7. The lithography system of claim 6, wherein: when the mask table mechanism can axially displace relative to the first movement mechanism, the mask table mechanism comprises a first axial movement mechanism and a second axial movement mechanism, the fixed end of the second axial movement mechanism is connected with the movable end of the first axial movement mechanism, and the mask pattern is arranged at the movable end of the second axial movement mechanism, so that the position of the mask plate with the mask pattern can be adjusted.

8. The lithography system of claim 6, wherein: the mask table mechanism further comprises a first vertical movement module, and the movement end of the first vertical movement module is connected with the fixed end of the first axial movement mechanism.

9. The lithography system of claim 5, wherein: the first motion mechanism comprises a pair of third axial motion mechanisms and a pair of fourth axial motion mechanisms, wherein the movable end of each third axial motion mechanism is connected with the fixed end of each fourth axial motion mechanism, and the movable end of each fourth axial motion mechanism is connected with the second motion mechanism.

10. The lithography system of claim 5, wherein: the second motion mechanism comprises a fifth axial motion mechanism and a sixth axial motion mechanism, the fifth axial motion mechanism is provided with a movable end which is connected with the fixed end of the sixth axial motion mechanism, and the sixth axial motion mechanism is provided with a movable end which can move relative to the fifth axial motion mechanism.

11. The lithography system of claim 10, wherein: the photoetching system is further provided with a second vertical movement module, the second vertical movement module is arranged between the bearing platform and the movable end of the sixth axial movement mechanism, the second vertical movement module is provided with a fixed end connected with the movable end of the sixth axial movement mechanism, and the second vertical movement module is provided with a movable end used for being connected with the bearing platform.

12. The lithography system of claim 5, wherein: the photoetching system further comprises at least one measuring mechanism, wherein the measuring mechanism is close to the second motion mechanism and used for measuring the displacement of the second motion mechanism relative to the first motion mechanism.

13. The lithography system of claim 5, wherein: the photoetching system also comprises a focusing and leveling mechanism, wherein the focusing and leveling mechanism is connected with the projection objective lens and is used for measuring the appearance of the upper surface of the silicon chip and the distance between the upper surface of the silicon chip and the optimal focal plane of the objective lens and establishing the relation between the upper surface of the silicon chip and the optimal focal plane of the objective lens.