CN109690416B

CN109690416B - Dense extreme ultraviolet lithography system with distortion matching

Info

Publication number: CN109690416B
Application number: CN201780037914.7A
Authority: CN
Inventors: 麦可·B·宾纳德
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 2016-06-20
Filing date: 2017-06-15
Publication date: 2021-12-21
Anticipated expiration: 2037-06-15
Also published as: WO2017222919A1; JP2019518246A; KR102458400B1; KR20190020088A; EP3472672A4; EP3472672A1; CN109690416A

Abstract

An extreme ultraviolet lithography system (10) for producing a new pattern (330) having a plurality of densely packed parallel lines (332) on a workpiece (22), the system (10) comprising: a patterning element (16); an EUV illumination system (12) that directs an extreme ultraviolet beam (13B) at the patterning element (16); a projection optics assembly (18) that directs the extreme ultraviolet light beam diffracted from the patterning element (16) at the workpiece (22) to produce a first strip (364) of substantially parallel lines (332) during a first scan (365); and a control system (24). The workpiece (22) includes a distorted existing pattern (233). The control system (24) selectively adjusts control parameters during the first scan (365) such that the first strip (364) distorts to more accurately cover the portion of the patterned underlying the first strip (364).

Description

Dense extreme ultraviolet lithography system with distortion matching

Cross Reference to Related Applications

The present application claims the following U.S. provisional patent applications: U.S. provisional patent application Ser. No. 62/352,545, entitled "Dense Line Extreme Ultraviolet laser System with Distation Matching", filed on 20/6/2016; U.S. provisional patent application Ser. No. 62/353,245, entitled "Extreme ultrasound System for fat considerations Pattern Stitching", filed on 22/6/2016; and U.S. provisional patent application serial No. 62/504,908 entitled "Illumination System with current 1D-Patterned Mask for Use in EUV-Exposure Tool", filed on 11.5.2017. As to licensing, the contents of U.S. provisional patent applications serial No. 62/352,545, serial No. 62/353,245, and serial No. 62/504,908 are all incorporated herein by reference for all purposes.

The present application also claims priority from U.S. patent application No.15/599,148 entitled EUV lithology System for sense Line Patterning, filed 2017,

month

5, 18. In addition, the present application also claims priority from U.S. patent application No.15/599,197 entitled "EUV lithology System for sense Line Patterning" filed on 2017,

month

5, 18. As to licensing, the contents of U.S. patent application No.15/599,148 and U.S. patent application No.15/599,197 are incorporated herein by reference for all purposes.

As for licensing, U.S. provisional patent application: U.S. provisional patent application serial No. 62/338,893, entitled EUV lithology System for sense Line Patterning, filed on 19/5/2016; U.S. provisional patent application serial No. 62/487,245, entitled "Optical Objective for sensitive Line Patterning in EUV Spectral Region", filed 19/4/2017; and U.S. provisional patent application serial No. 62/490,313 entitled "Illumination System With Flat id-Patterned Mask for Use in EUV-Exposure Tool", filed 2017, 26/4, are hereby incorporated by reference for all purposes.

Technical Field

The present invention relates to an exposure tool used in a photolithography process of a semiconductor workpiece, and more particularly, to an exposure tool configured to form parallel line patterns spaced apart from each other by several tens of nanometers or less on a workpiece.

Background

Lithography systems are commonly used to transfer an image from a patterning element (patterning element) onto a workpiece during exposure. Next generation lithography techniques may use Extreme Ultraviolet (EUV) lithography to enable the fabrication of semiconductor workpieces with extremely small feature sizes.

Disclosure of Invention

One embodiment pertains to an extreme ultraviolet lithography system that produces a new pattern having a plurality of densely packed parallel lines on an already patterned workpiece (e.g., a semiconductor wafer) that includes distortions. The lithography system includes a patterning element having a patterning element pattern; a workpiece stage mover assembly that holds and moves the workpiece relative to the patterning element; directing an extreme ultraviolet beam (e.g., light having a wavelength of about 13.5 nm) to an EUV illumination system at the patterning element; a projection optics assembly that directs the extreme ultraviolet beam diffracted from the patterning element at the workpiece to produce a first band of densely-packed parallel lines on the workpiece, the densely-packed parallel lines extending generally along a first axis; and a control system that controls the stage assembly to move the workpiece relative to the exposure field during the first scan along a first scan trajectory that is substantially parallel to the first axis. As provided herein, the control system selectively adjusts control parameters during the first scan such that the first band of parallel lines more accurately covers the portion of the already patterned parallel lines that are under the first band of parallel lines relative to the case where the control parameters are not adjusted.

In one embodiment, the control parameters include selectively adjusting the first scan trajectory during the first scan to include a portion moving along a second axis perpendicular to the first axis and a portion moving about a third axis perpendicular to the first and second axes such that the first band of parallel lines more accurately covers the portion of the patterned parallel lines that are under the first band. Said movement along said second axis and about said third axis during said first scan is a function of the position of the workpiece of said stage along said first axis.

Additionally or alternatively, the control parameters may include selectively adjusting a magnification (magnification) of the patterned element pattern image during the first scan so that the first strip of parallel lines more accurately covers portions of the patterned parallel lines that are located under the first strip. Further, the control parameters may include selectively adjusting a magnification tilt (i.e., a linear change in magnification across the exposure field) of the patterned element pattern image during the first scan so that the first strip of parallel lines more appropriately covers portions of the patterned pattern that lie under the first strip of parallel lines.

In one embodiment, the existing pattern comprises a plurality of previously patterned dies (also referred to as exposure "shots" or "fields", since each shot may contain more than one pattern or semiconductor device), and the control system controls the EUV illumination system such that every other die along the first scan trajectory is not exposed during the first scan. Subsequently, the control system may control the EUV illumination system to expose unexposed dies along the first scan trajectory during a second scan.

In another embodiment, the control system controls the EUV illumination system to stop the first scan and reset the first scan trajectory at an interface of adjacent dies.

As provided herein, the control system can selectively adjust the first scan trajectory and spacing of the parallel lines transferred to the workpiece during the first scan such that the first band of parallel lines is distorted to more accurately cover the portion of the patterned parallel lines that are under the first band.

Yet another embodiment relates to a method for transferring a new pattern having a plurality of dense fill lines onto an already patterned workpiece that includes distortion. The method may comprise the steps of: (i) providing a patterned element having a patterned element pattern; (ii) moving the workpiece with a workpiece table mover assembly; directing an extreme ultraviolet beam at the patterning element with an EUV illumination system; (iii) directing the extreme ultraviolet light beam diffracted from the patterning element at the workpiece with a projection optics assembly to produce the plurality of densely-packed parallel lines on the workpiece as the workpiece is moved relative to an exposure field during a first scan, the first band of parallel lines extending generally along a first axis; and (iv) controlling the workpiece stage assembly with a control system during the first scan to move the workpiece relative to the exposure field along a first scan trajectory substantially parallel to the first axis; the control system includes a processor; wherein the control system selectively adjusts control parameters during the first scan such that the first swath of parallel lines more accurately covers the portion of the patterned swath that lies below the first swath of parallel lines.

Embodiments pertain to devices manufactured using the lithography system and/or workpieces (e.g., semiconductor wafers) that have had images formed thereon by the lithography system.

Drawings

The novel features of the invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which like reference numerals refer to like parts, and in which:

FIG. 1A is a simplified schematic diagram illustrating an extreme ultraviolet lithography system having features of the present embodiment;

fig. 1B is a simplified side view of a shutter assembly (shutter assembly) having features of the present embodiment;

FIG. 2A is a simplified top view of a workpiece that has been processed to include an already patterned workpiece;

FIG. 2B is a simplified diagram illustrating raw wide distortion data for a workpiece processed with a step and repeat lithography system or a step and scan lithography system;

FIG. 2C is a simplified diagram illustrating only global distortion data for the workpiece;

FIG. 2D is a simplified diagram illustrating distortion data for each die of a workpiece;

fig. 2E includes a diagram illustrating a common distorted shape of the grains;

FIG. 2F includes a diagram illustrating residual distortion data;

fig. 3A is a flowchart illustrating a process having the features of the present embodiment;

FIG. 3B is a simplified top view of a workpiece including a first strip of parallel lines;

FIG. 3C is a simplified top view of a workpiece including a first strip of parallel lines and a second strip of parallel lines;

FIG. 3D is a simplified top view of a portion of a pattern of patterning elements projected onto a workpiece;

FIG. 3E is a simplified top view of another portion of a pattern of patterning elements projected onto a workpiece;

FIG. 3F is a simplified top view of a portion of a workpiece, wherein a portion of a new pattern overlays an existing pattern;

FIG. 4A is a simplified top view of a workpiece having a first portion of a first strip of parallel lines;

FIG. 4B is a simplified top view of a workpiece having a second portion of a first strip of parallel lines;

FIG. 4C is a simplified top view of yet another first strip of work pieces and parallel lines;

fig. 5A is a flowchart outlining a process for manufacturing a device according to the present embodiment; and

fig. 5B is a flow chart outlining the device process in more detail.

Detailed Description

Fig. 1A is a simplified, non-exclusive schematic diagram illustrating an Extreme Ultraviolet (EUV) lithography system 10, the EUV lithography system 10 comprising: an EUV illumination system 12 (irradiation device) that produces an initial EUV beam 13A (shown in dashed lines), a patterning element stage assembly 14 that holds a patterning element 16 having a patterning element pattern 16A, a projection optics assembly 18, a workpiece stage assembly 20 that holds and positions a workpiece 22 (which may be a semiconductor wafer), a control system 24 that controls operation of the components of the system 10, and a shutter assembly 26 that defines the shape of an exposure field 28 produced with the shaped and diffracted EUV beams 13D, 13E on the workpiece 22. The design and location of these components may vary in accordance with the teachings provided herein.

In addition, it should be noted that the EUV lithography system 10 typically includes more components than are shown in fig. 1A. For example, the EUV lithography system 10 may include a rigid device frame (not shown) for holding one or more components of the system. Furthermore, the EUV lithography system 10 may include one or more temperature control systems (not shown) that control the temperature of one or more components of the EUV lithography system 10. For example, the EUV illumination system 12, the patterning device 16, the projection optics assembly 18, and/or the workpiece stage assembly 20 may need to be cooled using a temperature control system.

Additionally, for example, the EUV system 10 may include an enclosed chamber 29 that enables many components of the EUV lithography system 10 to operate in a controlled environment (such as a vacuum).

By way of overview, the EUV lithography system 10 directs an exposure field 28 onto a workpiece 22 that is being moved along a scan trajectory to transfer a new pattern 330 (shown in fig. 3B) comprising only a plurality of densely-packed substantially parallel lines 332 onto a semiconductor workpiece 22 that already comprises an existing pattern 233 (shown in fig. 2A). In some embodiments, the EUV lithography system 10 adjusts one or more control parameters, such as the scan trajectory of the workpiece 22, the magnification of the image of the patterning element pattern 16A, and/or the magnification tilt of the image of the patterning element pattern 16A, while scanning and exposing the workpiece 22, such that the new pattern 233 follows and more closely covers the existing pattern 233 than if the one or more control parameters were not adjusted. Thus, in one embodiment, the present embodiment creates an imperfect new pattern 330 of densely packed substantially parallel lines to better match and better cover the distorted existing pattern 233. Furthermore, in some embodiments, the EUV lithography system 10 may be controlled to produce discontinuities between adjacent grains along the scan trajectory. More specifically, the EUV lithography system 10 may be controlled to scan each strip of parallel lines twice over the workpiece 22, exposing every other die in a first pass and exposing alternate dies in a second pass.

In summary, the EUV lithography system 10 is uniquely designed to more accurately match and cover the distorted existing pattern 233 on the workpiece 22 with the new pattern 330 of lines by adjusting the scan trajectory, magnification, and "magnification tilt" of the patterning device pattern 16A while scanning and exposing the workpiece 22. The existing pattern is typically distorted because of workpiece distortion and the nature of the layers that create the existing pattern 233. With this embodiment, the new patterned element pattern 330 is printed to be distorted in a more closely matching manner.

Some of the figures provided herein include an orientation system that specifies X, Y, and Z axes that are orthogonal to one another. In these figures, the Z-axis is oriented in the vertical direction. It should be understood that the orientation system is merely for reference and may be varied. For example, the X-axis may be switched with the Y-axis and/or the EUV lithography system 10 may be rotated. Further, these axes may alternatively be referred to as a first axis, a second axis, or a third axis. For example, the Y-axis may be referred to as a first axis, the X-axis may be referred to as a second axis, and the Z-axis may be referred to as a third axis.

The EUV illumination system 12 includes an EUV illumination source 34 and an illumination optical assembly 36. The EUV illumination source 34 emits an initial EUV beam 13A, and the illumination optics 36 direct and condition the EUV beam 13A from the illumination source 34 to provide a conditioned EUV beam 13C that is directed to the patterning element 16. In fig. 1A, the EUV illumination system 12 includes a single EUV illumination source 34 and a single illumination optical assembly 36. Alternatively, the EUV illumination system 12 may be designed to include a plurality of EUV illumination sources 34 and a plurality of illumination optical assemblies 36.

As provided herein, the EUV illumination source 34 emits an EUV beam 13A in the EUV spectral range. As provided herein, the "EUV spectral range" shall mean and include wavelengths between about 5 nanometers and 15 nanometers, and preferably within a narrow band of about 13.5 nanometers. As a non-exclusive example, the EUV illumination source 34 may be a plasma system, such as a Laser Produced Plasma (LPP) or a Discharge Produced Plasma (DPP).

Illumination optics assembly 36 is reflective and includes one or more optical elements operable in the EUV spectral range. More specifically, each optical element comprises a working surface which is coated to reflect light in the EUV spectral range. Furthermore, the optical elements are spaced apart from each other.

In fig. 1A, the illumination optical assembly 36 includes: a first illumination optics 38, a second illumination optics 40, and a third illumination optics 42 that cooperate to condition the initial EUV beam 13A and direct the conditioned EUV beam 13C at the patterning element 16. In one embodiment, first illumination optics 38 is a fly's-eye type reflector comprising a plurality of individual micro-reflectors (micro-mirrors or facets) arranged in a two-dimensional array, wherein each reflector comprises a working surface coated to reflect light in the EUV spectral range. Similarly, the second illumination optical element 40 is a fly's eye-type reflector comprising a plurality of individual micro-reflectors (micro-mirrors or facets) arranged in a two-dimensional array, wherein each reflector comprises a working surface which is coated to reflect light in the EUV spectral range. Furthermore, the third illumination optical element 42 is a reflector, which comprises a working surface coated to reflect light in the EUV spectral range. In certain embodiments, the

illumination optics

38, 40, 42 comprise curved surfaces for focusing EUV light.

In fig. 1A, the EUV illumination source 34 emits an initial EUV beam 13A generally downward to a first illumination optic 38. The plurality of micro-reflectors of the first illumination optics 38 reflect and redirect the EUV beam generally upward to the second illumination optics 40. Somewhat similarly, the plurality of micro-reflectors of the second illumination optics 40 reflect and redirect the EUV beam generally downward at the third illumination optics 42. Next, the third illumination optics 42 act as a relay that collects the conditioned EUV beam 13C, reflects the conditioned EUV beam 13C, and focuses the conditioned EUV beam 13C substantially uniformly upward onto the patterning element surface 16A of the patterning element 16. It should be noted that the facet mirror of the first illumination optics 38 forms an image of the EUV illumination source 34 at each facet mirror of the second illumination optics 40. In response, the faceted mirror of the second illumination optics 40 reflects the uniform image of the first illumination optics 38 onto the patterning element 16 via the third illumination optics 42. In the illustrated embodiment, an intermediate image of the first illumination optics 38 is formed at an intermediate image plane 56 between the illumination optics 40 and the illumination optics 42. In other words, each facet of the second illumination optics 40 is optically conjugate to the EUV source 34 and the third illumination element 42, while each facet of the first illumination optics 38 is optically conjugate to the intermediate image plane 56 and the patterning element 16. For this arrangement, the image field of each reflector surface of the first illumination optics 38 is overlaid at the patterning element 16 to form a sufficiently uniform irradiation pattern on the patterning element 16.

Patterning device stage assembly 14 holds patterning device 16. In certain embodiments, the patterning element stage assembly 14 may be designed to fine tune the position and/or shape of the patterning element 16 to improve the imaging performance of the EUV lithography system 10. For example, in certain embodiments, patterning element stage assembly 14 may shape, position, and/or move patterning element 16 to change and adjust the magnification of exposure field 28, and to change the magnification tilt of exposure field 28. In one non-exclusive example, the patterning device stage assembly 14 may include a patterning device stage 14A, and a patterning device stage mover 14B. In the non-exclusive embodiment shown in fig. 1A, patterning element table 14A is monolithic and includes a patterning element holder (not shown) that holds patterning element 16. For example, the patterning element holder may be an electrostatic chuck (electrostatic chuck) or a part of another type of chuck.

The patterning member stage mover 14B controls and adjusts the positions of the patterning member stage 14A and the patterning member 16. For example, patterning device stage mover 14B may move and position patterning device 16 in six degrees of freedom (e.g., along and about the X, Y, and Z axes). Alternatively, patterning device stage mover 14B may be designed to move patterning device 16 in less than six degrees of freedom (e.g., in three degrees of freedom). Furthermore, in certain embodiments, patterning member stage mover 14B and/or patterning member holder may be controlled by control system 24 to distort patterning member 16 by stretching, bending, or compressing patterning member 16 as desired. As provided herein, patterning device stage mover 14B may include one or more piezoelectric actuators, planar motors, linear motors, voice coil motors, attraction-only actuators, and/or other types of actuators. In some embodiments, the range of motion of patterning device stage 14A is relatively small.

The patterning element 16 diffracts the conditioned EUV beam 13C to produce an image that is projected onto the workpiece 22. For example, patterned element 16 may be a diffraction grating. In one embodiment, the patterning element pattern 16A of the patterning element 16 comprises a periodic structure that reflects and diffracts the conditioned EUV beam 13C in multiple directions (including a first diffracted EUV beam 13D and a second diffracted EUV beam 13E that travel away from the patterning element 16 in different directions). In one embodiment, the periodic structure of patterning element 16 includes a pattern of parallel lines parallel to the Y-axis. In an alternative embodiment, the patterning element 16 may be a periodic structure that changes the phase and/or intensity of the EUV beam 13C. For example, the periodic structure may be a pattern of reflected and non-reflected lines at the proper spacing to produce the desired diffracted beam. Alternatively, the periodic structure may be a line pattern that changes the optical phase of the EUV light to produce the desired diffracted beam.

The projection optics 18 direct the diffracted EUV light beams 13D, 13E to form an image of the patterning element 16 on a photosensitive photoresist material on a semiconductor workpiece 22 located at an image plane of the projection optics 18. In one embodiment, the projection optics assembly 18 is reflective and includes one or more optical elements operable in the EUV spectral range. More specifically, each optical element component comprises a working surface which is coated to reflect light in the EUV spectral range. Furthermore, the optical elements are spaced apart from each other.

In fig. 1A, the projection optics 18 direct EUV light (including the first and second diffracted EUV beams 13D and 13E) reflected from the patterning element 16 at the workpiece 22. In other words, with the present embodiment, light waves diffracted or scattered from patterned element 16 are collected by projection optics assembly 18 and recombined to generate an image of patterned element 16 on workpiece 22. Because the patterning element 16, which scatters/diffracts the EUV beam, is imaged onto the workpiece 22, the edges appear as sharp boundaries in the resist of the workpiece 22. One of the significant advantages of the projection optical system 18 is therefore that it allows the exposure field 28 to have well-defined edges. In FIG. 1A, projection optics assembly 18 includes a first projection subassembly 44 and a second projection subassembly 46 that cooperate to form an image of a pattern of patterned elements on workpiece 22. In contrast, if the projection optical system 18 only directs two diffracted EUV beams 13D, 13E to form an interference pattern on the workpiece 22, the edges will appear unfocused and blurred.

For example, (i) the first projection subassembly 44 may include a left first projection optic 44A and a right first projection optic 44B that cooperate to direct reflected EUV light; and (ii) the second projection subassembly 46 may include left and right

second projection optics

46A, 46B that cooperate to direct reflected EUV light. In one embodiment, each first projection

optical element

44A, 44B is a reflector comprising a working surface coated to reflect light in the EUV spectral range. Similarly, each second projection

optical element

46A, 46B is a reflector comprising a working surface coated to reflect light in the EUV spectral range. In certain embodiments,

optical elements

44A, 44B are formed as part of a single EUV mirror. Similarly, the

optical components

46A, 46B may be formed as part of a single EUV mirror. Depending on the particular application,

optical elements

44A, 44B may be two portions of a single curved mirror, or they may be separate components. Similarly,

optical elements

46A, 46B may be two portions of a single curved mirror, or they may be separate components.

Workpiece stage assembly 20 holds workpiece 22, positions and moves workpiece 22 relative to exposure field 28 to produce a pattern 330 of parallel lines that are densely packed on workpiece 22. As a non-exclusive example, workpiece stage assembly 20 may include a workpiece stage 48 and a workpiece stage mover 50 (illustrated as a block).

In the non-exclusive embodiment shown in fig. 1A, workpiece stage 48 is unitary and includes a workpiece holder (not shown) that holds workpiece 22. For example, the workpiece holder may be an electrostatic chuck or a part of another type of clamp.

The workpiece stage mover 50 controls and adjusts the position of the workpiece stage 48 and the workpiece 22 relative to the exposure field 28 and the rest of the EUV lithography system 10. For example, the workpiece stage mover 50 may move and position the workpiece 22 in six degrees of freedom (e.g., along and about the X, Y, and Z axes). Alternatively, the workpiece stage mover 50 may be designed to move the workpiece 22 in less than six degrees of freedom (e.g., in three degrees of freedom). As provided herein, the workpiece stage mover 50 may include one or more planar motors, linear motors, voice coil motors, attraction-only actuators, and/or other types of actuators.

In some embodiments, the scan speed may vary depending on the size of the exposure field 28. Further, in certain embodiments, the workpiece stage mover 50 moves the workpiece 22 at a substantially constant speed during each scan pass.

Control system 24(i) is electrically connected to workpiece stage assembly 20 and directs and controls electrical current to workpiece stage assembly 20 to control the position of workpiece 22; (ii) electrically connected to the patterning element stage assembly 14 and directing and controlling electrical current to the patterning element stage assembly 14 to control the position and/or shape of the patterning element 16; (iii) is electrically connected to the EUV illumination system 12 and guides and controls the EUV illumination system 12 to control the EUV beam 13; and (iv) electrically connected to shutter assembly 26 and directing and controlling shutter assembly 26 to adjust the shape of exposure field 28. Control system 24 may include one or more processors 54 and electronic data storage.

In the exclusive example of shutter assembly 26 being EUV light, shutter assembly 26 shapes the EUV beam such that exposure field 28 has a generally rectangular shape.

FIG. 1B is a simplified side view of a non-exclusive example of a shutter assembly 26. In this embodiment, the shutter assembly 26 includes a rigid shutter housing 26A that defines a housing aperture 26B (shown in phantom), a movable shutter 26C (shown in frame), and a shutter mover 26D (shown in frame). In this embodiment, the housing aperture 26B generally defines the shape and size of the exposure field 28 (as shown in FIG. 1A). However, in this embodiment, the movable shutter 26C may be selectively moved relative to the housing aperture 26B by the shutter mover 26D to selectively cover a portion, cover all, or uncover the housing aperture 26B to adjust the size of the exposure field 28 along the Y-axis (shown in fig. 1A).

In fig. 1B, the movable shutter 26C includes a shutter opening 26E. With this design, the movable shutter 26 may be moved back and forth to selectively and alternatively adjust the size of the exposure field 28 from either direction along the Y-axis (scan direction).

Further, the shutter mover 26D may be a motor controlled by the control system 24 (shown in fig. 1A) to selectively and alternatively adjust the size of the exposure field 28 from either direction along the Y-axis during the scanning process according to the scan direction. In alternative embodiments, shutter assembly 26 may include additional brakes or moving components to allow modification of the shape of exposure field 28 to correct for non-uniformity or other effects of EUV illumination.

Referring back to fig. 1A, shutter assembly 26 may be positioned at a plurality of different positions along a beam path 55 between EUV illumination source 34 and workpiece 22. For example, shutter assembly 26 may be positioned along beam path 55 (i) near patterning element 16, (ii) near workpiece 22, or (iii) at or near an intermediate image plane. In the embodiment shown in fig. 1A, the shutter assembly 26 is positioned along the beam path 55 at an intermediate image plane 56 between the second illumination optics 40 and the third illumination optics 42. Thus, the conditioned EUV beam 13C directed to the patterning element 16 has been shaped. In an alternative embodiment having an intermediate image plane at another location, such as between patterning element 16 and workpiece 22, pattern shutter 26 may be positioned at the intermediate image plane (not shown) along beam path 55.

It should be noted that any of the EUV beams 13A, 13C, 13D, 13E may be collectively referred to as an EUV beam. Furthermore, as used herein, the term beam path 55 shall refer to the path of the EUV beam traveling from the illumination source 34 to the workpiece 22.

Fig. 2A is a simplified top view of a workpiece 22, which workpiece 22 has been machined to include an existing pattern 233 (only a portion of which is illustrated as a small circle) having a plurality of adjacent dies 260 (also referred to as "shot", or "die") on the workpiece 22. The design of the existing pattern 233 and the number, size, and shape of the die 260 may vary. In the non-exclusive example shown in FIG. 2A, the workpiece 22 has been machined to include ninety-six rectangular grains 260. Further, for a workpiece 22 having a diameter of 300 millimeters, each die 260 may be, for example, 26 millimeters (along the X-axis) by 33 millimeters (along the Y-axis). However, other numbers and other sizes are possible. The center of each die 260 is identified by a plus sign. Each die 260 can be created on the workpiece 22 using a step and repeat lithography system or a step and scan lithography system (not shown) that exposes an area on the workpiece 22 to create one of the dies 260 and then steps to another area to create another die 260. This process is repeated until all the existing patterns 233 are completed.

Unfortunately, as provided herein, the existing pattern 233 on the workpiece 22 is often distorted. As non-exclusive examples, distortion of the existing pattern 233 may be caused by temperature changes of the workpiece 22 during various processing steps, residual stresses in the workpiece 22, clamping of the workpiece 22, etching of the workpiece 22, clamping of a reticle (reticle) used in a step and repeat lithography system, and/or irregularities in the projection optics of the step and repeat lithography system.

Fig. 2B is a simplified diagram illustrating raw wide distortion data for a workpiece 22 processed using a step and repeat lithography system. It should be noted that the raw distortion data will be different for each workpiece 22. In fig. 2B, distortion is represented by a plurality of minute vectors (arrows) 262 at a plurality of alternately spaced locations on the workpiece 22. These vectors 262 illustrate how the existing pattern 233 (shown in FIG. 2A) is distorted at those particular locations relative to the desired pattern (not shown). In general, the magnitude of vector 262 represents the magnitude of the distortion and the direction represents the direction of the distortion from its proper location.

In FIG. 2B, the X-axis and Y-axis dimensions of the workpiece 22 are also illustrated for reference. In this example, the workpiece 22 has a diameter of 300 millimeters. It should be noted that for the workpiece 22 shown in fig. 2B, the distortion is highest in the lower right quadrant and lowest in the upper left quadrant.

As a non-exclusive example, the distortion data may be generated by accurately measuring the existing pattern 233 and comparing the existing pattern 233 with the expected pattern.

It should be noted that the wide distortion data shown in fig. 2B includes two primary effects, namely, (i) how the workpiece 22 is globally stretched or distorted, and (ii) how each die 260 is distorted.

Fig. 2C is a simplified diagram illustrating only global distortion data (with small arrows) for the workpiece 22. In other words, fig. 2C is a linear fit of the data illustrating how the entire workpiece 22 is distorted. This may also be referred to as inter-shot distortion data or workpiece distortion data.

It should be noted that for workpiece 22 shown in fig. 2C, the global distortion of workpiece 22 is highest in the lower right quadrant and lowest in the upper left quadrant.

For example, the global distortion data in fig. 2C may be generated by fitting a linear equation of the X and Y distortion components to the raw data shown in fig. 2B.

Fig. 2D is a graph illustrating distortion data (with small arrows) for each die 260 of the workpiece 22. It should be noted that the distortion of each die 260 is approximately the same (consistent and repeating) for the workpiece 22 shown in fig. 2D. This is because the grain distortion from step and repeat exposure processes or step and scan exposure processes is typically caused by gravity sag of the reticle (not shown) used during exposure, temperature fluctuations of the reticle, deformation of the reticle caused by clamping, and deformation characteristics of the projection lens assembly of the lithography system. The grain distortion may also be referred to as intra-shot distortion data.

It should be noted that the grain distortion data may be calculated by subtracting the workpiece distortion data from fig. 2C from the wide total distortion data from fig. 2B.

Fig. 2E shows a plot generated using the grain distortion data from fig. 2D to estimate the common distortion shape for each of ninety-six grains 260. In fig. 2E, the figure illustrates the common distortion shape for each die generated using a linear polynomial equation (first order correction).

Fig. 2F illustrates residual distortion data. More specifically, the residual distortion data shown in fig. 2F is obtained by subtracting the graph of fig. 2E from the grain distortion data of fig. 2D.

FIG. 3A is a simplified flowchart illustrating steps taken to overlay and match a new pattern 330 generated by the EUV lithography system 10 of FIG. 1A to an existing pattern 233. More specifically, at block 300, distortion data for an existing pattern on a workpiece is determined. Once the distortion data for the workpiece is determined, one or more control parameters required to cause the new pattern to overlay the existing pattern 302 are determined at block 302. In other words, using the distorted data of the existing pattern 233, the desired location and characteristics of the new pattern 330 can be determined such that the plurality of lines of the new pattern 330 match and overlay the distorted existing pattern 233. As provided herein, one or more control parameters for each scan to create the new pattern 330 may be determined such that the new pattern 330 covers the distorted existing pattern 233. Steps 300 and 302 may be performed off-line and before starting the exposure of the new pattern 330.

As non-exclusive examples, the control parameters of the EUV lithography system 10 during generation of the new pattern 330 may include adjustments for each scan trajectory (e.g., X-axis offset of the workpiece, theta z-axis (θ z) rotation of the workpiece), magnification changes of the patterned element pattern during one or more scans, and/or magnification tilt of the patterned element pattern during one or more scans. Furthermore, these control parameters may be determined based on the X and/or Y axis position of the workpiece. Determining the desired new pattern and each of these control parameters may be found by several potential methods: (i) fitting a polynomial or other analytical expression to the measured data; (ii) interpolating between the measurement points and smoothing any discontinuities; (iii) solving an optimization problem that minimizes residual errors while maintaining trajectories that satisfy platform constraints on velocity, acceleration, and jerk (jerk); and (iv) smoothing the trajectory using a digital filter.

Next, at block 304, the new pattern 330 is transferred to the workpiece 22 using the control parameters. More specifically, the EUV lithography system 10 shown in fig. 1A may be controlled to match and overlay the existing pattern 233 with the new dense line pattern 330 across the entire workpiece 22 by adjusting the scan trajectory, magnification, and magnification tilt of the patterned element pattern while scanning and exposing the workpiece 22 to compensate for distortion of the workpiece 22 during previous processing. With this design, the EUV lithography system 10 will generate the new pattern 330 in a matching manner and distort the new pattern 330 such that the new pattern 330 is more accurately aligned with the existing pattern 233 already present on the workpiece 22 than if the control parameters were not adjusted.

FIG. 3B is a simplified illustration of a workpiece 22 including a portion of a new pattern 330 of parallel lines 332 formed using the EUV lithography system 10 of FIG. 1A. At this point, only the first strip 364 of densely packed substantially parallel lines 332 has been transferred to the workpiece 22. However, upon completion, substantially the entire surface of the workpiece 22 will include densely packed substantially parallel lines 232. It should be noted that the X-axis spacing and shape of line 332 is greatly exaggerated in fig. 3B for clarity. In this embodiment, each parallel line 332 extends across the entire workpiece 22 generally parallel to the Y-axis and perpendicular to the X-axis. It should be noted that the parallel lines 332 shown in fig. 3B are merely illustrative. It should be appreciated that in one (i.e., semiconductor wafer) non-exclusive embodiment, the spacing (pitch) between adjacent parallel lines 332 may be in the range of ten (10) nanometers to forty (40) nanometers. It should be understood, however, that this range of spacing should not be construed as limiting. Parallel lines 332 having a pitch of less than ten (10) nanometers (for example) or greater than forty (40) nanometers (for example) may be patterned onto the workpiece 22 using the EUVL tool 10. In alternative non-exclusive examples, adjacent parallel lines 332 may have a pitch of less than 70 nanometers, 60 nanometers, 50 nanometers, 40 nanometers, 30 nanometers, 20 nanometers, 10 nanometers, or 5 nanometers. Further, as used herein, the phrase "densely packed" means a substantially continuous line pattern although in most cases, the densely packed lines will cover substantially the entire workpiece surface, which is by no means a requirement. In alternative embodiments, the parallel lines may have periodic gaps and/or variations in spacing.

FIG. 3B also illustrates a rectangular exposure field 28 created on the workpiece 22 by the EUV lithography system 10 of FIG. 1A. In this example, a first strip 364 of parallel lines 332 is transferred to the workpiece 22 during a first scan 365 of the workpiece 22 relative to the exposure field 28. In the first scan 365, the stage mover 50 (shown in FIG. 1A) is controlled to move the workpiece 22 (down the page in FIG. 3B) relative to the exposure field 28 along a first scan trajectory 366 (shown with thicker dashed lines) to create a first swath 364 of parallel lines 332. In fig. 3B, the first scan trajectory 366 is sawtooth-shaped and extends substantially parallel to the Y-axis. More specifically, in the first scan, the first scan trajectory 366 is generally along the Y-axis, but includes some movement along the X-axis and about the Z-axis so that the new pattern 330 matches the existing pattern 233. As provided herein, the movement of the workpiece 22 along the X-axis and about the Z-axis during the first scan anchor may be a function of the position of the workpiece 22 along the Y-axis.

In addition, as provided herein, the magnification of the patterning element pattern 16A (shown in fig. 1A) and the magnification of the patterning element tilt of the patterning element pattern 16A may be changed during the first scan 365 such that the new pattern 330 closely covers the existing pattern 233. For example, in some embodiments, adjusting the focus position of patterning element 16 (shown in FIG. 1A) or workpiece 22 will produce a magnification change of parallel lines 332. With this effect, the patterning element 16 and/or the workpiece 22 can be moved slightly in the focus direction, so that the pitch of the printed lines 332 changes slightly. Furthermore, by slightly tilting patterning element 16 and/or workpiece 22 about the Y-axis, a "magnification tilt" may be produced in which the print pitch varies linearly across exposure field 28 in the X-direction.

Further, in fig. 3B, the first swath 364 comprises eight spaced-apart lines, which represent only a very large number (e.g., millions) of densely packed lines printed onto the workpiece 22 during a single scan along the first scan trajectory 366. In one embodiment, the width of the first strip 364 of lines 332 (and the exposure field 328 on the workpiece 22) may be a few millimeters wide. For example, the width of the exposure field 328 may be about 5 millimeters wide. As alternative, non-exclusive examples, the spacing (pitch) between adjacent parallel lines 232 may be less than about 5 nanometers, 10 nanometers, 20 nanometers, 30 nanometers, 40 nanometers, 50 nanometers, 60 nanometers, or 70 nanometers. As provided herein, "densely packed" refers to a generally continuous line pattern without any significant variation in gaps or spacings.

As shown in fig. 3B, in certain embodiments, during printing of a continuous first swath 364 across a workpiece 22 using the EUV lithography system 10, it may be necessary to make relatively abrupt changes to the first scan trajectory 366 at each boundary 367A (which is highlighted by the dashed oval) of adjacent dies 260 (shown in fig. 2A). In other words, during the first scan 365, the first scan trajectory 366 can extend generally along the Y-axis with an abrupt discontinuity 367B at each boundary 367A of adjacent dies 260. These discontinuities 367B are necessary to adjust the first scan trajectory 366 at these boundaries 367A so that the first strip 364 covers the existing pattern 233 printed on the die 260 using a step and repeat lithography system or a step and scan lithography system. It should be noted that in fig. 3B, the new pattern 330 is transferred across nine dies 260 aligned in columns. Thus, there are eight boundaries 367A, and the first scan trajectory 366 includes eight discontinuities 367B.

In some embodiments, to continuously transfer the first strip 364, the workpiece 22 may need to be moved slowly during the first scan 365 and/or the system may need to be designed such that the exposure field 28 has a relatively small Y-axis dimension 328. For example, in alternative proprietary examples, the Y-axis dimension 328 may be less than about 0.2 millimeters, 1 millimeter, 2 millimeters, 3 millimeters, 5 millimeters, or 10 millimeters.

After the first swath 364 is created, the workpiece 22 may be stepped along the X-axis and then scanned in the opposite direction to create the next swath of parallel lines. The scanning process and the stepping process are performed alternately until the entire pattern 330 of parallel lines 332 is created on the workpiece 22.

More specifically, FIG. 3C is a simplified illustration of a workpiece 22, the workpiece 22 including, in addition to a first strip 364 formed using the EUV lithography system 10 of FIG. 1A, a second strip 368 of parallel lines 332 (shown in short dashed lines).

FIG. 3C also illustrates a rectangular exposure field 28 created on the workpiece 22 by the EUV lithography system 10 of FIG. 1A. In this example, a second strip 368 of parallel lines 332 is transferred to workpiece 22 during a second scan 369 of workpiece 22 relative to exposure field 28. In a second scan 369, stage assembly 20 (shown in FIG. 1A) is controlled to move workpiece 22 (upward in the figure) relative to exposure field 28 along a second scan trajectory 370 (shown in bold dashed lines) to create a second swath 368 of parallel lines 332. In fig. 3B, the second scan trajectory 370 is sawtooth-shaped and extends substantially parallel to the Y-axis. More specifically, in second scan 369, second scan trajectory 370 is generally along the Y-axis, but includes some movement along the X-axis and about the Z-axis, such that new pattern 330 matches existing pattern 233. As provided herein, movement along the X-axis and about the Z-axis may be a function of the position of the workpiece 22 along the Y-axis. These adjustments will allow for the printed new pattern 330 to be aligned with the average displacement of the existing pattern 233 in the X direction and for the patterned element lines 332 to "turn around" when the patterned element lines 332 are printed across the diameter of the workpiece 22.

Additionally, as provided herein, the magnification of patterning element pattern 16A (shown in fig. 1A) and the magnification tilt of patterning element pattern 16A may be changed during second scan 369 such that new pattern 330 closely overlays existing pattern 233 as compared to if these adjustments were not made.

It should be noted that the second scan trajectory 370 is slightly different from the first scan trajectory 366 because the distortion of the workpiece 22 is different in this region. Thus, the second strip 368 is slightly different from the first strip 364.

Accordingly, as provided herein, the

scan trajectories

366, 370, magnification, and/or magnification tilt of the workpiece 22 relative to the exposure field 28 can be varied for and during each

scan

365, 369 to customize each

swath

364, 368 to more accurately cover the existing pattern 233. In other words, the

scanning trajectories

366, 370, the magnification, and the magnification tilt may be different for different regions based on the amount of distortion of the existing pattern 233.

Fig. 3D is a simplified illustration of a portion of the first strip 364 being transferred to the workpiece 22. In this figure, a portion of the first scan trajectory 366 is illustrated with a thicker dashed line, and a leftmost line 332L and a rightmost line 332R are illustrated. In this embodiment, the first scan trajectory 366 is generally along the Y-axis, but includes some movement along the X-axis and about the Z-axis such that the new pattern 330 matches the existing pattern 233.

It should be noted that the first strip 364 has a strip width 372 measured generally along the X-axis between the

lines

332L, 332R. As provided herein, exposure apparatus 10 provided herein is controlled to selectively adjust the magnification of patterned element pattern 16A directed to workpiece 22 during scanning to selectively adjust a swath width 372 of first swath 364 along scan trajectory 366 such that first swath 364 matches existing pattern 233. In fig. 3D, the strip width 372 decreases from top to bottom. However, the swath width 372 may be varied in any manner as desired along the first scan trajectory 366 such that the first swath 364 more accurately covers the existing pattern 233 than would be the case without magnification adjustment.

As a non-exclusive example, adjustment of the focus position of the patterning element 16 (shown in fig. 1) or the workpiece 22 will produce a magnification change that changes the swath width 372 along the first scan trajectory 366. With this effect, the patterning element 16 and/or the workpiece 22 can be moved slightly in the focus direction (up or down in the Z-axis) by means of the respective stage assembly to cause a small change in the pitch of the printed

lines

332L, 332R (selectively adjusting the pitch). In another embodiment, patterning element pattern 16A (shown in fig. 1A) may be selectively mechanically stretched or compressed along the X-axis by patterning element stage assembly 14 to vary magnification. Still alternatively, the temperature of the patterning element 16 may be adjusted to mechanically change the pitch of the patterning element pattern 16A.

Fig. 3E is a simplified illustration of another portion of the first strip 364 being transferred to the workpiece 22. In this figure, a portion of the first scan trajectory 366 is illustrated with a thicker dashed line, and again illustrates the leftmost line 332L and the rightmost line 332R. In this embodiment, the first scan trajectory 366 is again generally along the Y-axis, but includes some movement along the X-axis and about the Z-axis so that the new pattern 330 more closely matches the existing pattern 233 than if the scan trajectory were unadjusted.

It should be noted that the first strip 364 has (i) a left intermediate width 374L measured generally along the X-axis between the leftmost line 332L and the scan trajectory 366, and (ii) a right intermediate width 374R measured generally along the X-axis between the rightmost line 332R and the scan trajectory 366. As provided herein, the exposure apparatus 10 provided herein is controlled to selectively adjust the magnification tilt of the pattern of patterning elements 16A directed at the workpiece 22 during scanning to selectively adjust the left and right

intermediate widths

374L, 374R such that the first strip 364 matches the existing pattern 233. In fig. 3E, (i) the

intermediate widths

374L, 374R are approximately equal at the top, and (ii) the left intermediate width 374L is greater than the right intermediate width 374R near the bottom due to adjustment of the magnification tilt. However, the

intermediate widths

374L, 374R can be varied in any manner as desired along the first scanning trajectory 366 such that the first strip 364 covers the existing pattern 233.

As non-exclusive examples, adjustment of the magnification tilt may be achieved by rotating patterned member pattern 16A about the Y-axis with patterned member stage mover 14B (shown in fig. 1A) or rotating workpiece 22 about the Y-axis with stage assembly 20 (shown in fig. 1A). By slightly tilting patterning element 16 and/or workpiece 22 about the Y-axis, a "magnification tilt" may be produced in which the print pitch of

lines

332L, 332R varies linearly across the exposure field in the X-direction. For example, patterning element 16 may be rotated slightly about the Y-axis in a first direction to decrease left intermediate width 374L and rotated slightly about the Y-axis in an opposite second direction to increase left intermediate width 374L.

All adjustments provided herein will enable improved alignment of the printed refresh pattern 330 with the average displacement of the existing pattern 233 in the X-direction, as well as "turning" of the patterned element lines 332 as they are printed across the workpiece 22.

Fig. 3F is an enlarged, simplified illustration of a portion of the existing pattern 233 (shown with small circles representing points on the existing pattern) and a portion of the first strip 364 of the new pattern 330 transferred to the workpiece 22. Fig. 3F illustrates how the first strip 364 is customized to closely cover the existing pattern 233. It should be noted that in the middle of each die, the first strip 364 closely covers the existing pattern 233. However, at the boundary 367A (which is highlighted by a dashed oval) of the adjacent grain 260 (which is shown by a dashed line), there may be some difference between the first strip 364 and the existing pattern 233 due to the rapid change at the boundary 367A of the adjacent grain 260.

Several alternative methods for controlling the EUV lithography system 10 such that the first strip 364 can better follow the existing pattern 233 at boundary 367A are provided herein.

For example, FIG. 4A is a simplified illustration of the workpiece 22 illustrating yet another first scan 465 of the workpiece 22 along a first scan trajectory 466 through the exposure field 28. In this embodiment, the euv lithography system 10 (shown in fig. 1A) is controlled such that every other die 260 (illustrated as a dashed rectangle) in the row of die 480 along the first scan trajectory 466 is not exposed during the first scan 465. In this example, during the first scan 465, the workpiece 22 is moved such that nine dies 260 aligned in the die column 480 along the Y-axis pass under the exposure field 28. It should be noted that these grains 260 have been previously created, and for clarity only one grain column 480 is illustrated in fig. 4A. Also, moving from the bottom to the top of the die column 480, the die 260 have been labeled 1-9 for ease of discussion.

In this example, euv lithography system 10 is controlled such that each odd-numbered die 260 (e.g., die 1, 3, 5, 7, 9) is exposed during first scan 465 along first scan trajectory 466 to create first portion 464F of the first strip, and each even-numbered die 260 (e.g., die 2, 4, 6, 8) is not exposed during first scan 465 along first scan trajectory 466. With this design, the stage assembly 20 can be controlled during the first scan 465 to better match the first portion 464F to the existing pattern 233 (shown in fig. 2A) at the boundaries 467A of the odd-numbered die 260. Essentially, during the first scan 465, the regions of even-numbered dies 260 provide time to move the workpiece 22 to the appropriate relative position for accurately printing the next odd-numbered die 260. In summary, in first scan 465, only "odd" dies 260 are exposed by interpolating smooth tracks with exposure light turned off (and/or blocked by shutter assembly 26 shown in FIG. 1A) while passing over "even" dies 260.

Subsequently, euv lithography system 10 is controlled to expose unexposed die along first scan trajectory 466 during second scan 469. FIG. 4B is a simplified illustration of workpiece 22 illustrating a second scan 469 of workpiece 22 through exposure field 28 along a second scan trajectory 470. In this embodiment, euv lithography system 10 (shown in fig. 1A) is again controlled such that every other die 260 (illustrated as a dashed rectangle) in die column 480 along second scan trajectory 470 is not exposed during second scan 469.

In this example, euv lithography system 10 is controlled such that each even-numbered die 260 (e.g., die 2, 4, 6, 8) is exposed during second scan 469 along second scan trajectory 470 to create second portion 464S of first strip, and each odd-numbered die 260 (e.g., die 1, 3, 5, 7, 9) is not exposed during second scan 469. With this design, the stage assembly 20 may be controlled during the second scan 469 to better match the second portion 464S with the existing pattern 233 at the boundaries 467A of the even-numbered dies 260. Essentially, during second scan 469, the area of odd-numbered die 260 provides time to move workpiece 22 to the appropriate relative position for printing the next even-numbered die 260. Thus, in a second pass through the same area, even grains 260 are exposed using smooth interpolation while passing through odd grains 260 that have already been exposed.

It should be noted that the previously printed first portion 464F is not shown in fig. 4B for clarity. However, referring to fig. 4A and 4B, the first and

second portions

464F, 464S cooperate to form a complete first strip of substantially parallel lines. It should also be noted that the

scan trajectories

466, 470 partially overlap but are not exactly the same. With this design, the workpiece 22 must be scanned twice through the exposure field 28 to completely create the new pattern.

In some embodiments, shutter assembly 26 (shown in FIG. 1A) may be used to accurately start and stop exposure at the boundaries 467A of the die 260. In this embodiment, shutters 26C are used to selectively define the Y-axis edges of exposure field 28. With this design, the shutter 26C can be used to open and close in conjunction with scanning. More specifically, the shutter 26C may be controlled to close gradually as it approaches the boundary 467A and to close completely at the boundary 467A. Subsequently, the shutter 26C may be controlled to gradually open at the beginning of the next die 260. Alternatively, for example, the EUV illumination source 34 may be turned on and off as needed to start and stop exposure.

With this design, the problem of matching successive scan exposures to layers printed with conventional tools that produce discontinuities between adjacent shots is solved by scanning each swath on the workpiece twice, exposing every other shot in the first pass, and exposing alternating shots in the second pass.

In yet another embodiment, referring to FIG. 4C, if workpiece 22 is scanned relative to exposure field 28 at a relatively low scan speed and stage assembly 20 (shown in FIG. 1A) has high acceleration capability, then exposure may be stopped at boundary 467A of each die 260 and workpiece 22 may be stopped and reversed. Subsequently, exposure may begin at the next die 260. With this design, the EUV illumination system 10 shown in fig. 1A is controlled to stop exposure at the interface 467A of adjacent dies 260 and to reset the scan track 492. In one embodiment, when the exposure field 28 reaches the interface 467A, the shutter 26 begins to close so that adjacent dies 260 are not exposed. Once the shutter is closed and exposure is stopped, the stage is decelerated and accelerated in the opposite Y direction in a reverse movement. When the platform has reversed its position sufficiently, it decelerates again and accelerates in the scan direction so that it is properly positioned when it again reaches the interface 467A. When the exposure field 28 starts to pass through the interface 467A, the EUV illumination system 10 is controlled to resume illumination and the shutter 26 starts to open. Thus, during scan 490, scan trajectory 492 (shown in solid bold lines) includes a reverse movement along the Y-axis during exposure of first swath 494 (only the outer lines are shown in dashed lines).

With this design, the problem of matching continuous scan exposures to layers printed with conventional tools that create discontinuities between adjacent dies 260 is solved by stopping and resetting at each die 260. Thus, the first strip 494 and subsequent strips will better cover the existing pattern 233 at the border 467A.

As described above, the lithography system according to the above-described embodiment can be constructed by assembling various subsystems (including each element listed in the appended claims) in such a manner that prescribed mechanical accuracy, electrical accuracy, and optical accuracy are maintained. To maintain various accuracies, each optical system is adjusted to achieve its optical accuracy before and after assembly. Similarly, each mechanical system and each electrical system are adjusted to achieve their respective mechanical and electrical accuracies. The process of assembling each subsystem into a lithography system includes mechanical interfaces, circuit wiring connections, and gas pressure piping connections between each subsystem. It goes without saying that there is also a process of assembling each subsystem before assembling the lithography system from the individual subsystems. Once the lithography system is assembled using the various subsystems, overall adjustments are made to ensure that accuracy is maintained throughout the lithography system. In addition, it is desirable to fabricate the exposure system in a clean room where temperature and cleanliness are controlled.

Further, the semiconductor device may be fabricated using the above-described system by the process generally shown in fig. 5A. In step 501, the functional and performance characteristics of the device are designed. Next, in step 502, a mask (reticle) having a pattern is designed according to the previous design steps, and in parallel step 503, the workpiece is made of silicon material. In step 504, the mask pattern designed in step 502 is exposed onto the workpiece from step 503 by the above-described lithography system according to the present embodiment. In step 505, the semiconductor device is assembled (including dicing, bonding, and packaging processes), and finally, the device is inspected in step 506.

Fig. 5B illustrates a detailed flowchart example of the above step 504 in the case of manufacturing a semiconductor device. In fig. 5B, in step 511 (oxidation step), the surface of the workpiece is oxidized. In step 512(CVD step), an insulating film is formed on the surface of the workpiece. In step 513 (electrode forming step), an electrode is formed on the workpiece by vapor deposition. In step 514 (ion implantation step), ions are implanted into the workpiece. The above-mentioned

steps

511 and 514 form pre-processing steps for the workpiece during processing of the workpiece, and are selected at each step according to the processing requirements.

At each stage of the workpiece processing, when the above-described preprocessing step has been completed, the following post-processing steps are carried out. During post-processing, first, in step 515 (photoresist forming step), a photoresist is applied to the workpiece. Next, in step 516 (exposure step), the circuit pattern of the mask (reticle) is transferred to the workpiece using the exposure apparatus described above. Then, in step 517 (developing step), the exposed workpiece is developed, and in step 518 (etching step), a portion (exposed material surface) other than the residual photoresist is removed by etching. In step 519 (photoresist removal step), the unwanted photoresist remaining after etching is removed.

A plurality of circuit patterns are formed by repeating these preprocessing and post-processing steps.

While the assembly shown and disclosed herein is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

1. An extreme ultraviolet lithography system for transferring a pattern of parallel lines onto a workpiece comprising a pattern, the lithography system comprising:

a workpiece stage assembly that holds and moves the workpiece;

an EUV illumination system directing an extreme ultraviolet beam at a patterning element defining the pattern of parallel lines;

a projection optics that projects and transfers an image of a plurality of parallel lines within an exposure field onto the workpiece as the workpiece moves relative to the exposure field during a first scan, the exposure producing a first band of the imaged plurality of lines extending generally along a first axis; and

a control system that controls the workpiece stage assembly to move the workpiece relative to the exposure field during the first scan along a first scan trajectory, the first scan trajectory being generally along the first axis;

wherein a positional relationship of the extreme ultraviolet light beam with the patterning element along the first axis is unchanged during the first scan,

the control system selectively adjusts control parameters during the first scan of the workpiece stage assembly such that the first band of parallel lines is distorted according to distortion of the patterned portion lying under the first band of parallel lines, thereby covering the patterned portion more accurately than without adjusting the control parameters.

2. The euv lithographic system according to claim 1, wherein the control parameters include selectively adjusting the first scan trajectory during the first scan to include a portion of movement along a second axis perpendicular to the first axis such that the first strip of parallel lines more accurately covers the portion of the patterned parallel lines that lies under the first strip of parallel lines than if no movement along the second axis were performed.

3. The euv lithographic system according to claim 2, wherein said control parameters comprise selectively adjusting said first scan trajectory during said first scan to include a portion moving about a third axis perpendicular to said first and second axes such that said first strip of parallel lines more accurately covers the portion of the patterned parallel lines that lies under said first strip.

4. The euv lithographic system according to claim 3, wherein during the first scan the movement along the second axis or about the third axis is a function of the workpiece position of the workpiece along the first axis relative to the case in which no movement along the second axis or about the third axis is performed.

5. The euv lithography system according to claim 1, wherein said control parameters include selectively adjusting the magnification of said plurality of parallel lines during said first scan such that said first band of parallel lines more accurately covers the portion of the patterned parallel lines that lies under said first band of parallel lines than would be the case without adjusting said magnification.

6. The euv lithography system according to claim 1, wherein said control parameters include selectively adjusting the magnification tilt of said plurality of parallel lines during said first scan such that said first band of parallel lines more accurately covers the portion of the patterned parallel lines that lies under said first band.

7. The euv lithography system according to claim 1, wherein the control parameter comprises selectively adjusting one or more of: (i) adjusting the first scan trajectory during the first scan to include a portion of movement along a second axis perpendicular to the first axis and a portion of movement about a third axis perpendicular to the first axis and the second axis; (ii) adjusting a magnification of the pattern of patterned elements during the first scan; and (iii) adjusting a magnification tilt of the patterned element pattern during the first scan.

8. The EUV lithography system according to claim 1, wherein the existing pattern comprises a plurality of dies, and wherein the control system controls the EUV illumination system such that every other die is not exposed along the first scan trajectory during the first scan.

9. The EUV lithography system according to claim 8, wherein the control system controls the EUV illumination system to expose unexposed dies along the first scan trajectory during a second scan.

10. The EUV lithography system of claim 1, wherein the existing pattern comprises a plurality of grains,

the control system controls the EUV irradiation system such that a first die of a plurality of dies along the first scanning trajectory is exposed during the first scan, and a second die adjacent to the first die of the plurality of dies along the first scanning trajectory is not exposed during the first scan, and a first die of the plurality of dies along the first scanning trajectory, which is located on an opposite side of the first die with respect to the second die, is exposed during the first scan.

11. The euv lithography system according to claim 1, wherein said existing pattern comprises a plurality of dies, wherein said control system stops exposure at an interface of adjacent dies, and wherein said control system controls said workpiece stage assembly to move said stage in a manner that resets said first scanning trajectory such that a new pattern overlays said existing pattern during exposure of a subsequent die.

12. An EUV lithography system according to claim 11, wherein EUV illumination is stopped by a shutter assembly located at or near a plane optically conjugate to the workpiece.

13. The euv lithography system according to claim 11, wherein the workpiece stage assembly resets the first scan trajectory by:

decelerating the stage to stop a scanning motion;

accelerating the table in the opposite direction;

decelerating the stage to stop reverse motion;

the stage is accelerated to resume scanning.

14. The euv lithography system according to claim 1, wherein the control system selectively adjusts the first scan trajectory and the spacing of the parallel lines transferred to the workpiece during the first scan such that the first band of parallel lines is distorted to cover the portion of the patterned parallel lines that are under the first band.

15. A method for transferring a pattern having a plurality of parallel lines to a patterned workpiece including distortions, the method comprising the steps of:

providing a patterned element having a patterned element pattern;

moving the workpiece with a workpiece table mover assembly;

directing an extreme ultraviolet beam at the patterning element with an EUV illumination system;

imaging the pattern of patterning elements onto the workpiece using projection optics, thereby creating the plurality of parallel lines on the workpiece as the workpiece is moved relative to an exposure field during a first scan, a first band of parallel lines extending generally along a first axis; and

controlling a workpiece stage assembly with a control system during the first scan to move the workpiece relative to the exposure field along a first scan trajectory, the first scan trajectory being generally along the first axis;

the control system selectively adjusts control parameters during the first scan such that the first band of parallel lines is distorted according to distortion of the patterned portion lying within the first band of parallel lines to more accurately cover the patterned portion than would be the case without adjusting the control parameters.

16. The method of claim 15, wherein the step of controlling comprises: controlling the workpiece table assembly during the first scan such that the first scan trajectory includes a portion moving along a second axis perpendicular to the first axis such that the first strip of parallel lines more accurately covers the portion of the patterned parallel lines that lies under the first strip.

17. The method of claim 16, wherein the step of controlling comprises: controlling the workpiece table assembly during the first scan such that the first scan trajectory includes a portion moving about a third axis perpendicular to the first axis and the second axis such that the first strip of parallel lines more accurately covers the portion of the patterned parallel lines that lies under the first strip.

18. The method of claim 17, wherein the control parameters include selectively adjusting magnification of the pattern of patterning elements during the first scan so that the first swath of parallel lines more accurately covers portions of the patterned swath that lie under the first swath of parallel lines.

19. The method of claim 15, wherein the control parameters include selectively adjusting a magnification tilt of the pattern of patterning elements during the first scan such that the first strip of parallel lines more accurately covers portions of the patterned that lie under the first strip of parallel lines.

20. The method of claim 15, wherein the step of controlling comprises selectively adjusting at least one of: (i) adjusting the first scan trajectory during the first scan to include movement along a portion of a second axis perpendicular to the first axis and/or movement about a portion of a third axis perpendicular to the first axis and the second axis; (ii) adjusting a magnification of the pattern of patterned elements during the first scan; and (iii) adjusting a magnification tilt of the patterned element pattern during the first scan.

21. The method of claim 15, wherein the existing pattern comprises a plurality of dies, and wherein controlling comprises controlling the EUV illumination system such that every other die is not exposed along the first scan trajectory during the first scan.

22. The method of claim 21, further comprising the steps of: controlling the EUV illumination system to expose unexposed die along the first scan trajectory during a second scan.

23. The method of claim 15, wherein the existing pattern comprises a plurality of grains,

24. The method of claim 15, wherein the existing pattern comprises a plurality of grains, and wherein the method comprises the steps of: controlling the EUV illumination system with the control system to stop and reset the first scan trajectory at an interface of adjacent dies.

25. The method of claim 15, comprising selectively adjusting, with the control system, the first scan trajectory and spacing of the parallel lines transferred to the workpiece during the first scan such that the first band of parallel lines is distorted to cover portions of the patterned parallel lines that are under the first band.