HK1085015A - Continuous direct-write optical lithography - Google Patents

Description

Continuous direct write lithography

no marking

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional application No.60/406,030, filed 24/8/2002, and is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates to the field of lithography, and in particular to printing patterns on: a wafer; a printed circuit board; a flat panel display; a mask; a reticle; and printing plates for the replication of magazines, newspapers and books.

Background

The semiconductor industry uses very expensive stepper tools for the photolithography process. Furthermore, very expensive reticles are used in this process-the cost of a reticle is sufficient to make the production of small batches of chips (e.g. custom ASICs) too expensive. The semiconductor industry requires lower cost photolithographic processing. Furthermore, each time the lithographic patterning is changed, it takes several days or longer to produce a new reticle. The semiconductor industry needs a lithographic process that can quickly adapt to patterning variations.

The Printed Circuit Board (PCB) industry has similar problems with applying photolithographic techniques. Furthermore, substrates used in the PCB industry are subject to distortion during manufacturing that limits the use of high resolution lithographic processing and the use of steppers on smaller areas of the substrate. High resolution lithographic processing is required for use with larger PCB substrates in which patterning is quickly and economically adjusted to accommodate distortions that vary from one substrate to another.

U.S. patents US5,330,878, US5,523,193, US5,482,818, and US5,672,464 to Nelson describe methods and apparatus for patterning substrates. The apparatus uses a Spatial Light Modulator (SLM), in particular a Deformable Mirror Device (DMD) of Texas Instruments, instead of a reticle. A DMD is an array of individually controllable reflective elements. The image of the DMD is projected onto a substrate through an imaging lens. Whether or not the individual elements of the DMD reflect light into the imaging lens so that it is projected onto the substrate, and is determined by the computer; the pattern projected on the substrate is computer controlled and easily changed. Improvements in this approach are required in order to meet both the semiconductor and PCB industries for high resolution and throughput requirements. Furthermore, it can be further used to reduce the cost of the apparatus while increasing the throughput and satisfying the requirement of high resolution.

Disclosure of Invention

The present invention provides an apparatus and method for patterning a photosensitive substrate. The apparatus includes a Spatial Light Modulator (SLM), a light source to illuminate the SLM, imaging optics to project an image of the SLM onto a substrate, and a device to move the image over a surface of the substrate. The SLM controls the pattern of light reaching the substrate. The SLM comprises at least one array of individually switchable elements (switchable between two or more states). The SLM may be a diffractive or transmissive device. The light source may be a continuous light source such as an arc lamp, LED or continuous laser; a quasi-continuous laser may also be used when the laser pulse frequency is much higher than the switching frequency of the elements of the SLM. The means for moving the image may be a platform on which the SLM or substrate is mounted. Where the substrate is in the form of a flexible film or the like, it may be moved using a roller-to-roller mechanism. As the image moves across the surface of the substrate, the elements of the spatial light modulator may be switched so that the pixels on the surface of the substrate receive energy doses sequentially from the elements of the spatial light modulator, thereby forming a latent image on the surface of the substrate. The imaging optics may be telecentric.

In a preferred embodiment, the imaging optics are configured to project a blurred image of the spatial light modulator onto the substrate, enabling sub-pixel resolution feature edge placement. Blurring can be achieved by: adjusting a focus of the imaging optics; adjusting the numerical aperture of the imaging optics; adding a diffuser between the SLM and the substrate; adding a micro lens array between the SLM and the substrate; or a combination of the foregoing.

In a preferred embodiment, the spatial light modulator is illuminated continuously, the image of the spatial light modulator is projected continuously onto the substrate, and the image is moved continuously across the surface of the substrate.

In certain embodiments, the SLM includes a plurality of area arrays. The corresponding imaging optics may be a single projection lens system or a plurality of projection lens systems. In the latter case, the number of area arrays is larger than the number of projection lens systems, and the number of projection lens systems is preferably a factor of the number of area arrays. Further, the plurality of area arrays may be disposed on one row, or they may be disposed in a plurality of rows, with the arrangement of the arrays staggered from row to row. The latter may utilize more imaging fields of the projection optics and may also result in more efficient exposure of the substrate-reducing the need for helical movement of the projected image of the SLM across the substrate during exposure.

Drawings

FIG. 1 is a schematic representation of a lithography tool with a movable substrate according to the present invention.

FIG. 2 is a schematic representation of a lithography tool having a movable spatial light modulator according to the present invention.

FIG. 3 is a schematic representation of a lithography tool with a flexible film substrate according to the present invention.

FIG. 4 is a detailed schematic representation of a first embodiment of the lithography tool of FIG. 1 illustrating telecentric projection optics.

FIG. 5 is a detailed schematic representation of a second embodiment of the lithography tool of FIG. 1 illustrating a spatial light modulator having a multi-domain array and corresponding sets of projection optics.

FIG. 6 is a detailed schematic representation of a third embodiment of the lithography tool of FIG. 1 illustrating a spatial light modulator having a multi-region array and a single set of telecentric projection optics.

FIG. 7 is a cross-sectional view of a portion of a micro mirror array according to the present invention, illustrating the array elements in the "on" and "off" positions.

FIG. 8 is a plan view of a substrate in accordance with the present invention that can be placed after a projected image of a spatial light modulator such that the entire substrate surface is exposed in a spiral path.

FIG. 9 is a plan view of a substrate in accordance with the present invention positioned after a projection image from each of a plurality of area arrays used together in order to expose the entire substrate surface in a spiral path.

Figure 10 is a diagrammatic representation of a process for forming a latent image according to the present invention.

Fig. 11 is a diagrammatic representation of the substrate array of fig. 10.

Fig. 12 is a graph showing the instantaneous light intensity distribution along line AB on the substrate of fig. 10 at equally spaced time intervals T/10 and starting at T3.

Fig. 13 is a graph showing the instantaneous light intensity distribution along line AB on the substrate of fig. 10 ending at equally spaced time intervals T/10 and to T4.

FIG. 14 is a graph showing the integrated dose distribution along line segment AB on the substrate of FIG. 10 due to exposure between times T3 and T4.

FIG. 15 is a graph showing the total dose distribution along line AB on the substrate of FIG. 10 due to exposure between times T1 and T7.

FIG. 16 is a graphical representation of a process for forming a latent image according to the present invention including a first example of edge translation by half the width of the mirror projection.

FIG. 17 is a graphical representation of a process for forming a latent image according to a second example of the present invention including half the projected width of the edge-shifting mirror.

FIG. 18 is a graphical representation of a process for forming a latent image according to the present invention including an example of one-fourth the projected width of an edge-shifting mirror.

FIG. 19 is a graphical representation of a process of forming a latent image including an example of three-quarters of the projected width of the edge-shifting mirror according to the present invention.

FIG. 20 is a graphical representation of a process of forming a latent image including an example of edge shifting one-fourth of the projected width of the mirror in another direction according to the present invention.

Fig. 21 is a graph showing the integrated dose distribution along line AB on the substrate of fig. 10, 16, 17, 18 and 19.

FIG. 22 is a further diagrammatic representation of the process of forming a latent image according to the present invention.

Figure 23 is a diagrammatic representation of the substrate array of figure 22.

FIG. 24 is a graph showing the integrated dose distribution along line segments CD, EF, GH and IJ on the substrate of FIG. 22.

FIG. 25 is a graphical representation of a process for forming a latent image including a further example of edge translation according to the present invention.

Fig. 26 is a diagrammatic representation of the substrate array of fig. 25.

FIG. 27 is a graph showing the integrated dose distribution along line segments KL, MN, OP, QR and ST on the substrate of FIG. 25.

FIG. 28 is a block diagram of a lithography system according to the present invention.

Figure 29 is a plan view of a structure of a multi-region array according to one embodiment.

FIG. 30 is a diagrammatic representation of another embodiment of the lithography tool of FIG. 4 illustrating an optical switching mechanism 121 in the path of light between the light source and the substrate.

FIG. 31 is a timing diagram for a lithography system having two spatial light modulators in a series configuration on an optical path according to the present invention.

FIG. 32 is a graphical representation of a process for forming a latent image using a lithography system having two spatial light modulators in a tandem configuration in the optical path according to the present invention.

FIG. 33 is a timing diagram of a lithography system having a spatial light modulator and an optical switching mechanism in series configuration in the optical path according to the present invention.

FIG. 34 is a schematic representation of a lithography tool having optics configured to overlap the projected images of two arrays of regions on the surface of a substrate in accordance with the present invention.

FIG. 35 is a timing diagram of the lithography system of FIG. 34.

Detailed Description

Referring to FIG. 1, a lithography tool 100 as one embodiment of the invention suitable for patterning a substrate 140 mounted on a movable stage 150 is shown, the lithography tool 100 having a light source 110, a Spatial Light Modulator (SLM)120 and imaging optics 130. Coordinate axes 160 are shown having z and y axes in the plane of the drawing and an x axis perpendicular to the plane of the drawing. The path of light through the lithography tool is represented by ray 170. The light source 110 continuously illuminates the SLM 120. The light source may include an arc lamp, a continuous laser (solid or gas), a Light Emitting Diode (LED), or other type of continuous light source having suitable spectral characteristics for exposure of the substrate 140. Furthermore, light sources such as quasi-continuous lasers (lasers emitting pulses at MHz frequency) may be suitable as light sources for the present invention-the frequency of the emitted pulses is well above the critical criteria of the switching frequency of the elements of the spatial light modulator (typically 104 Hz); in which case the illumination of the SLM by the light source is effectively continuous. The light source also includes optical components that increase the intensity of the illumination and improve the uniformity of the illumination. These may include elliptical mirrors, circular and elliptical lenses and light pipes or fly-eye lens arrays. The SLM120 is one or more area arrays (generally rectangular) of elements that act on the light beam from the light source. The image of the SLM is projected continuously onto the substrate by imaging optics 130 (also referred to as projection optics). The elements can be individually switched between two or more states, under computer control, to control the magnitude of light in the image. One embodiment of the present invention includes an SLM that is a diffractive element or mirror array of incident light that is switchable between two or more angular states. A Digital Micromirror Device (DMD), currently available from Texas instruments, is one example of a suitable mirror array that can be switched between two angular states. An example of a diffractive SLM is the Grating Light Valve (GLV) currently produced by Silicon Light Machines. Other embodiments of the present invention include an SLM as a Liquid Crystal Display (LCD) device. If the elements of the SLM are transmissive, rather than reflective, the optics need to be repositioned; such a rearrangement will be apparent to the person skilled in the art. The imaging optics 130 may contain reflective and refractive elements and are generally telecentric. The substrate 140 includes a photosensitive layer, such as a photoresist coating, or is itself a photosensitive material, such as a photosensitive polyimide sheet. The platform 150 may be a ball bearing or air bearing design and may have height adjustment (in the z-direction), tilt, and rotation capabilities. These types of stages are well known and commonly used in lithography systems. For simplicity of illustration, the substrate is assumed to be planar. However, the invention can also be used for other substrate shapes having rotatable rather than planar platforms, such as cylindrical or spherical.

Referring to FIG. 2, a lithography tool 200, which is one embodiment of the invention suitable for patterning a substrate 140, is shown having a light source 110, an SLM120, a stage 250 on which the SLM is mounted, and imaging optics 130. Its method of operation is the same as that of lithography tool 100 as described above, except that stage 250 moves SLM120 while substrate 140 is stationary during exposure. The imaging lens system 130 and/or the illumination source 110 may also be coupled to the stage 250 and move with the SLM.

Referring to FIG. 3, a lithography tool 300, which is one embodiment of the present invention suitable for patterning a flexible substrate 340, is shown having a light source 110, an SLM120, a stage 250 on which the SLM is mounted, imaging optics 130, and rotatable, spaced apart, axially parallel film rolls 342 and 344. The photosensitive flexible film substrate 340 is wrapped around and tensioned between film rollers 342 and 344 so that the film can move in the y-direction (with reference to the stationary frame 160). Both exposure modes are possible. In the first mode, the stage 250 moves the SLM in the x-direction at a constant speed while the substrate 340 is stationary. When the exposure pass is complete (e.g., to the edge of the substrate), the film roll points the substrate in the y-direction, and the stage reverses direction for the next exposure. The result is a helical exposure path similar to path 850 shown in fig. 8, which will be discussed in more detail below. While the stage is stationary, the film roll moves the substrate in the y-direction at a constant speed until the edge of the exposure area is reached. The stage then points the substrate in the x direction and the film roll is reversed for the next exposure. Furthermore, this results in a helical exposure path. Furthermore, if the width of the area exposed on the substrate is less than or equal to the width of the projected image of the SLM, the stage remains stationary or disappears and the film roll moves the substrate at a constant speed without reversing direction. As with the other embodiments, projection optics may be implemented on the platform.

Referring to fig. 4, 5, and 6, various embodiments of the lithography tool 100 (see fig. 1) are shown in detail.

FIG. 4 is a schematic diagram of a continuous direct-write lithography system with an arc lamp and a telecentric projection lens system. Successive shots from mercury arc lamp 410 are reflected from elliptical reflector 411. The reflected light (represented by light ray 170) travels to dichroic mirror 412, which dichroic mirror 412 reflects wavelengths useful for exposure of substrate 140 (e.g., 350 nm-450 nm) and is transparent to other wavelengths. Light that is not reflected from the dichroic mirror is absorbed in the illumination beam stream collector 413. Other types of lamps may be used, such as xenon arc lamps, depending on the desired exposure wavelength and source brightness. The light pipe 415 is used to improve illumination uniformity, but may be replaced with a fly-eye lens array. A light pipe lens system 414 disposed before the light pipe 415 is used to adjust the numerical aperture of the illumination system and to adjust the diameter of the light beam before entering the light pipe. The condenser lens system 416 captures the light coming out of the light pipe and changes the beam shape and angle to meet the requirements of the SLM 120. The condenser lens system includes an illumination aperture 417. The light pipe lens system and the condenser lens system are typically composite and comprise cylindrical lens elements. A continuous illumination mercury arc lamp, elliptical reflector, dichroic mirror, illumination beam stream collector, light pipe lens system, light pipe, condenser lens system, and illumination aperture comprise one embodiment of an illumination source 110, as shown in fig. 1. An SLM is one or more area arrays (typically rectangular) of small mirrors that can be switched between two or more angular states under computer control. At least one angular state reflects light from the illumination source into telecentric projection lens system 430 and at least one other angular state reflects the line into SLM beam dump 480. The Digital Micromirror Device (DMD) currently available from Texas Instruments is an example of a suitable mirror array that can be switched between two angular states. The mirrors in the "on" state in the SLM are imaged onto the substrate by a telecentric projection lens system. Light reflected from the mirror in the "off" state in the SLM travels to the SLM beam dump where it is absorbed. Further details of the operation of the SLM are provided below and in fig. 7. The substrate contains a photosensitive layer, such as a photoresist coating, or is itself a photosensitive material, such as a photosensitive polyimide sheet. The substrate is attached to a stage 150, which stage 150 is continuously moved during exposure on straight line segments in the x-y plane of a stationary coordinate system 160. The numerical aperture of the telecentric lens system is determined by the projection lens aperture 432, which is optically conjugate to the illumination aperture 417. A double telecentric projection lens system is shown. A telecentric design is preferred because magnification does not change with substrate height, which simplifies the calibration of the lithography tool for each substrate. The telecentric projection lens system is one type of projection lens system 130 as shown in fig. 1. The stage is movable in the x-y plane and in the z direction of a stationary coordinate system 160. The platform 150 also has rotational and tilting capabilities; this may be required for proper substrate alignment (e.g., when there is a problem with substrate planarity). The movement in the z direction focuses or defocuses the projected image on the substrate. A substrate height measurement system 450 utilizing a height detection medium 490 may be used to determine the z-position of the surface of substrate 140. The height measurement system may be optical, capacitive or air-based. The preferred type is the air type. Focusing can also be achieved by moving the SLM or the projection lens system in the z-direction.

FIG. 5 is a schematic diagram of a sequential direct-write lithography system with an arc lamp, an SLM with multiple area arrays, and multiple lens systems. The light sources are arranged as described above in FIG. 4, except that a condenser lens system 516 and lens array 518 captures the light exiting the light pipe 415 in order to improve beam shape and angle to meet the requirements of the individual SLM area arrays 520 through 524. The lens array maximizes the light intensity on a single SLM area array; the lens array is configured to match the configuration of the array of SLM areas, which may be arranged in a line, multiline (see fig. 29), or other two-dimensional configuration. Although the lens array is not a critical component, it is preferably incorporated. The lens array may include lenses arranged corresponding to the SLM area array; alternatively, the lenses in the lens array may be replaced with one or more diffractive elements. The light pipe lens system 414 and the condenser lens system 516 are generally dichroic and comprise cylindrical lens elements. Continuous illumination mercury arc lamp 410, elliptical reflector 411, dichroic mirror 412, illumination beam collector 413, light pipe lens system 414 light pipe 415, condenser lens system 516, and lens array 518 comprise one type of continuous illumination source 110 as shown in FIG. 1. Each individual SLM area array 520-524 is a rectangular array of small mirrors that can be switched between two or more angular states under computer control. The Digital Micromirror Device (DMD) currently available from Texas Instruments is an example of a suitable mirror array that can be switched between two angular states. The mirrors in the "on" state in SLM area array 520 are imaged by projection lens 530 onto substrate 140; the same is true for SLM area arrays 521 through 524 and their corresponding projection lenses 531 through 534. Light reflected from the SLM area array 520 in the "off" state travels to the SLM beam collector 480 where it is absorbed in the SLM beam collector 480; otherwise for SLM area arrays 521 through 524. In this example 5 per SLM area arrays (520 to 524), projection lenses (530 to 534) and substrate height measurement systems (550 to 554) are shown, but any number may be used. The lens may contain both reflective and refractive elements and is generally telecentric. The projection lens system (any of 530 to 534) may be the same as the imaging optics 130 of fig. 1. The substrate 140 may contain a photosensitive layer, such as a photoresist coating, or be itself a photosensitive material, such as a photosensitive polyimide sheet. The substrate is attached to a stage 150, which stage 150 moves continuously during exposure on straight line segments in the x-y plane of a stationary coordinate system 160. As with other embodiments, the imaging optics may be implemented on a platform.

FIG. 6 is a schematic diagram of a sequential direct write optical lithography system with a single telecentric objective system and an SLM with multiple area arrays. Light source 610 is the same as the light source described in FIG. 5 and is configured to provide illumination to meet the requirements of a single SLM area array 520 through 524. Each single SLM area array is a rectangular array of small mirrors that can be switched between two or more angular states under computer control. The Digital Micromirror Device (DMD) currently available from texas instruments is an example of a suitable mirror array that can be switched between two angular states. The mirrors in the "on" state in the SLM area array are imaged by projection lens 630 onto substrate 140. Light reflected from the array of SLM regions in the "off" state travels to SLM beam collector 480 where it is absorbed in SLM beam collector 480. In this example, 5 SLM area arrays are shown, but any number can be used. A double telecentric projection lens system 630 is shown. However, a single telecentric or non-telecentric projection system may also be used. A telecentric system is preferred because magnification does not change with substrate height, which simplifies calibration of the lithography tool or each substrate. The telecentric projection lens system is a projection lens system 130 of the type shown in fig. 1. The platform 150 is movable in the x-y plane and in the z direction of a stationary coordinate system 160. The platform 150 also has rotational and tilting capabilities; this may be required for proper substrate alignment (e.g., when there is a problem with substrate planarity). The movement in the z direction focuses or defocuses the projected image on the substrate. The z-position of the surface of substrate 140 can be determined using height measurement system 450. The height measurement system may be optical, capacitive or air-based. The preferred type is the air type. Focusing can also be achieved by moving the SLM area arrays 520 to 524 or the telecentric projection lens system 630 in the z-direction. The substrate 140 may contain a photosensitive layer, such as a photoresist coating, or be itself a photosensitive material, such as a photosensitive polyimide sheet.

With further reference to the lithography systems of FIGS. 5 and 6, other embodiments of the present invention can be devised that combine an SLM having multiple area arrays and a plurality of projection lens systems. For example, a lithography system may have 6 SLM area arrays and 2 projection lens systems, such that each projection lens system images 3 different SLM area arrays at a time. Furthermore, the number of projection lens systems need not be limited to mathematical factors-for example, a lithography system may have 7 SLM area arrays and 2 projection lens systems such that the first projection lens system images 3 SLM area arrays and the second projection lens system images the remaining 4 SLM area arrays. The structure of these embodiments will be apparent to those of ordinary skill in the art. It is clear that there are very many further combinations of SLM area arrays and projection lens systems, which combinations will be apparent to those of ordinary skill in the art in light of the teachings of this specification.

Referring to FIG. 7, a partial cross-section of SLM 720 is shown. Mirror 720 is shown in the "on" position and mirror 722 is shown in the "off" position. Light ray 770 reflects off the surface of the mirror 721 in the "on" position toward the substrate (ray 771) and off the surface of the mirror 722 in the "off" position toward the beam stop (ray 772). For example, referring to fig. 4 and 7, light ray 771 passes through projection lens system 430 and then reaches substrate 140, while light ray 772 falls outside the receiving aperture of projection lens system 430 and is collected by beam stop 480. This is the preferred mode of operation, although other modes of operation are contemplated. For example, light ray 772 may fall partially within the acceptance aperture of projection lens system 430, and thus the attenuated signal from the "off" state mirror will reach the substrate, which is acceptable.

Referring to fig. 8, an example is shown of a spiral path 850 after a projected image of an SLM in order to expose the entire surface of substrate 140. The motion of the image is due to the image motion mechanism. The substrate of the SLM may be mounted on an image movement mechanism. An example of a suitable mechanism is a platform such as that shown in figures 1, 2 and 3. In the case of a flexible substrate, a suitable mechanism is a pair of rotatably spaced axially parallel film rollers, as shown in FIG. 3. In the following explanation, it is assumed that a structure of a photolithography system in which a substrate is mounted on a stage is employed. Shown below are: substrate 140, spiral path 850, distance between straight line segments on path 851, substrate coordinate system 853, and stationary coordinate system 860. The SLM is oriented so that the columns of pixels in the projected image on the substrate are parallel to straight line segments of the helical path, which for ease of illustration are parallel to the x-axis stationary coordinate system 860. The stage positions substrate 140 so that the projected image of the SLM is centered at the beginning of path 850. In this example, at the beginning of path 850, none of the SLM's image falls on substrate 140. When the stage moves in the + x direction (with reference to the stationary coordinate system 860), the center of the projected image of the SLM moves in the-xs direction (with reference to the substrate coordinate system 853) and tracks the first straight portion of the spiral-like path. The exposure starts when the projected image of the SLM lands on the substrate. The exposure stops when the projection lens system passes the edge of the substrate. The stage then repositions the substrate in a standby state to scan in the-x direction along a second straight section of the path that is spaced apart from the first straight section in the y direction by a distance 851, all with reference to a stationary coordinate system 860. These are repeated until the entire substrate is exposed. Obviously, the projection width of the SLM must be greater than or equal to distance 851 in order to expose the entire substrate. If only a certain area of the substrate needs to be exposed, the spiral patterning can be performed more efficiently for each individual area. Although a spiral path is preferred, other paths may be used as long as they contain straight segments for exposure. It will be apparent to one of ordinary skill in the art that a spiral path may also be implemented by a lithography system configuration in which the SLM is mounted on a stage and the substrate is stationary.

Referring to FIG. 9, an example is shown of a set of spiral paths 950 through 954 followed by a projected image of a corresponding set of SLM area arrays to expose the entire surface of substrate 140. The movement of the image is caused by an image movement mechanism. The substrate or SLM may be mounted on an image motion mechanism. An example of a suitable mechanism is a platform such as that shown in figures 1, 2 and 3. In the case of a flexible substrate, a suitable mechanism is a pair of rotatably spaced axially parallel film rollers, as shown in FIG. 3. In the following explanation, it is assumed that a structure of a photolithography system in which a substrate is mounted on a stage is employed. Each SLM area array is oriented such that the columns of pixels in the projected image on substrate 140 are parallel to a straight segment of the spiral path (for ease of illustration) and parallel to an x-axis stationary coordinate system 860. The platform positions substrate 140 so that the projected image of the SLM is centered at the beginning of paths 950 to 954. In this example, at the beginning of paths 950 through 954, none of the SLM's image falls on substrate 140. When the stage moves in the + x direction (with reference to the stationary coordinate system 860), the center of the projected image of the SLM moves in the-xs direction (with reference to the substrate coordinate system 853) and tracks the first straight portion of the spiral-like path. The exposure starts along any path while the projected image of the SLM lands on the substrate. The exposure stops along any path as the projection lens system passes over the edge of the substrate. After all exposures have been stopped, the stage then repositions the substrate in the standby state to scan in the-x direction along a second straight section of the path that is spaced apart from the first straight section in the y direction by a distance 851, all with reference to a stationary coordinate system 860. If the entire substrate is not covered, the stage moves in the y-direction (with reference to the stationary frame 860) the distance between paths 950 and 954 and the procedure described above is repeated. Obviously, the projection width of the SLM must be greater than or equal to distance 851 in order to expose the entire substrate. Note that if in this example the pitch between the continuous paths 950, 951.. 954 is twice the interval 851, the pitch should exceed twice the interval 851, and then a helical motion with more straight portions can be utilized. This explanation is relevant to the multiple SLM area array lithography system of fig. 5 and 6, for which paths 950 to 954 correspond to SLM area arrays 520 to 524.

Referring to fig. 1 and 8, the pattern of elements corresponding to features printed on the substrate 140 in the "on" state must be moved across the SLM120 so that they appear, on average, stationary relative to a constantly moving substrate. If the stage 150 is moved at a constant velocity v (the stage is moved in the patterning direction) along one of the straight segments of the spiral path 850, then this is done by translating the SLM to pattern a line at regular intervals, where the time interval T is given by:

T＝pM/v (1)

where p is the pitch of the elements (Texas integers DMD mirrors have the same pitch for both rows and columns) and M is the magnification of projection lens system 130. By way of example, a Texas integers DMD may have a mirror pitch of 13.7 microns, and the minimum mirror cycle time is 102 microseconds. If projection lens system 130 has a magnification of 2.0, the stage speed is approximately 269 mm/s. The actual mirror cycle time used may need to be longer if the delivered dose is insufficient to expose the substrate or the required stage speed exceeds the capability of the stage system. However, the mirror period time and the stage velocity must always satisfy equation (1).

FIG. 10 shows a translation of a pattern on an SLM and a corresponding pattern on a substrate. In this example, the substrate is moved over a stage and in the x-direction at a constant speed during exposure. Referring also to fig. 1, the following is shown: a partial SLM120, which is an array of elements 1000 having 6 columns and four rows; a corresponding component of substrate 140, which is an array of pixels 1002 having an area of 6 columns and four rows; a resulting image 1007 having a projected line pitch (pixel width) 1008. The resulting image shows one possible latent image created on the substrate by the completion of the entire exposure sequence. Edge placement and corner rounding in the latent image will be discussed in more detail below. "snapshots" of corresponding portions of the SLM and the substrate are shown at equal intervals T1-T7, where the intervals satisfy equation (1); a part of the SLM and the substrate are denoted M and L, respectively, in the drawing. The SLM array 1000, substrate array 1002, and resulting image 1007 are depicted as looking down in the-z direction of the stationary coordinate system 160 from a position directly above them. For ease of illustration, in each "snapshot", the SLM and substrate are shown adjacent to each other. Projection row pitch 1008 in result image 1007 is the row pitch in SLM array 1000 multiplied by the magnification of projection lens system 130. However, for ease of illustration, in each "snapshot", the SLM and substrate are shown to have the same size and orientation. The grids shown in arrays 1000 and 1002 and image 1007 are for reference only. In 1000 light squares correspond to SLM elements in the "on" state, while dark squares correspond to SLM elements in the "off state. The light and dark regions in 1002 correspond to the states of the SLM elements of this "snapshot". For example, at time T1, the substrate is receiving light on pixels located at R1C4 and R1C5 (here the designation R1C4 represents a pixel/element on R1 row and column C4) from a mirror of the SLM array at locations R4C4 and R4C 5. At time T1, the bottom edge of substrate array 1002 is aligned with substrate position coordinate 1. At time T2, the substrate moved one row and the bottom edge of the substrate is now aligned with substrate position coordinate 2. The time elapsed between T2 and T1 satisfies equation (1). The particular feature pattern used as an example in FIG. 10 is shown in its entirety at time T4 on both the SLM and the substrate array. It can be seen that the edge of this feature pattern first appears at T1, rolls over the SLM array 1000 between times T2 and T6, and moves the SLM array 1000 away at T7. On the substrate 1002, the feature pattern does not move. These can be seen most clearly at times T3 and T4. However, because the substrate is moving at a constant speed while the SLM is stationary, the projected pattern actually moves the projected line pitch 1008 between any two consecutive snapshot times over the substrate. Note that the patterning shown on substrate array 1002 does not show any blurring or optical interference effects for ease of illustration.

FIG. 11 shows the substrate array 1002 having line segment AB located at the center of column C4. The light intensity and resulting dose distribution will be determined on the surface of the substrate array in the position indicated by line segment AB. Note that the position of AB is: which intersects the "trailing edge" of the exposure pattern shown in fig. 10.

The result of the movement of the projected pattern over the substrate surface during exposure is now examined. FIG. 12 shows the instantaneous light intensity distribution on the substrate array 1002 of FIG. 10; the position of the distribution along the line segment AB as shown in fig. 11. Note that in fig. 12, a line segment AB is shown extending from-2 to 1.5 on the abscissa. In FIG. 12, the six distributions shown are distributed at intervals of T/10 and begin at T3 and then are shown at every T/10, where T is defined in equation (1) above. The substrate is moved at a constant speed. The abscissa represents the substrate displacement Xs (as shown in fig. 8 and 9) measured in units of projected line space (as defined above with reference to fig. 10). The following is shown in figure 12: light intensity distributions 1200, 1201, 1202, 1203, 1204, and 1205; 50% of the intensity mark 1209; 50% of the position markers 1210; and a projected line pitch 1215. The light intensity distributions 1200, 1201, 1202, 1203, 1204, and 1205 are shown to be gaussian in shape; however, the actual shape depends on the details of the optics. The instantaneous light intensity as a function of position on substrate array 1002 at time T2 is represented by light intensity distribution 1200. Light intensity distribution 1200 is positioned such that the intersection of 50% of marks 1209 on the abscissa corresponds to the boundary between rows R3 and R4 on the substrate array. The region between-1 and 0 on the abscissa corresponds to R4 on the substrate array, and the region between 0 and 1 and the region between 1 and 2 correspond to R2. As the stage moves the substrate array 1002 in the + x direction, the instantaneous light intensity distribution passes through the substrate array in the-Xs direction. For time T3, light intensity distributions 1201, 1202, 1203, 1204 and 1205 are added with T/10, 2T/10, 3T/10, 4T/10 and 5T/10, respectively. In T/2 the light intensity distribution projects half the line pitch through the substrate in the-Xs direction. In this example, adding T/2 at T3, the elements in the SLM array 1000 switch from the pattern shown at T to the pattern shown in T4. Looking specifically at the array elements used to generate the light intensity distribution: the elements on C4R4 switch from "on" to "off, the elements on C4R3 and C4R2 remain" on ", and the elements on C4R1 switch from" off "to" on ". The result is to translate the light intensity distribution from the position of 1205 to a new position that is 1 times the projected line pitch in the + Xs direction.

Fig. 13 is a view showing the light intensity distribution of the next period T/2 after fig. 12. After the element is switched at time T3+ T/2, the light intensity distribution is moved from the position 1205 (fig. 12) to the position 1300 (refer to fig. 13). As the stage continues to move in the + x direction to the array of substrates 1002, the instantaneous light intensity distribution passes through the array of substrates in the-Xs direction. The light intensity distributions 1301, 1302, 1303, 1304, and 1305 are for time T3 plus 6T/10, 7T/10, 8T/10, 9T/10, and 10T/10, respectively. The light intensity distribution 1305 is time T3+ T, which is the same as time T4. In T2 the light intensity distribution projects half the line pitch through the substrate in the-Xs direction. Therefore, the position of the light intensity distribution 1305 at T4 is the same as the distribution 1200 at T.

Fig. 12 and 13 show how the light intensity distribution varies between time intervals T3 and T4. Fig. 14 shows the resulting dose distribution for the same location on the substrate array 1002 along line AB. The light intensity distributions 1200 and 1300 in fig. 12 and 13 are gaussian distributions having σ of 0.43. As can be seen in fig. 14, fig. 14 shows that the resulting dose distribution 1401 has a similar shape to the original gaussian distribution.

Shown in FIG. 14 are: the resulting dose distribution 1401, 50% of the location markers 1405 of the resulting dose markers 1404, 505, and the projection line pitch 1215. Because the elements in the SLM array 100 in fig. 10 switch as the substrate array 1002 moves by half the projection row pitch 1008, 50% of the resulting dose mark intersects the resulting dose distribution 1401 at location 1405, which is the same location as location 1210 in fig. 12 and 13. This is due to the symmetrical nature of the process shown in figures 12 and 13. In addition to Tn + T/2 (where n is 1, 2, 3.), other choices of element switching times (such as Tn + T/5) may be used. The shape of the resulting dose distribution may be the same as 1401, but 50% of the resulting dose positions on the abscissa will be shifted from 0. Obviously, the switching time can be used to control the position of the printed patterned edge. However, it is preferred to keep the switching time constant. The shape of the dose distribution is usually not the same as the instantaneous light intensity distribution. This means that the dose distribution parallel to the direction of movement of the platform will be different from the orthogonal dose. The edge parallel to the direction of motion of the platform will not move constantly and therefore the distribution of the dose on the substrate will be the same as its instantaneous light intensity distribution for such edge.

Returning to FIG. 10, the process of switching elements in SLM array 1000 at Tn + T/2 (where n is 1, 2, 3..) is repeated until the pattern has all scrolled through SLM array 1000, which in this example is at time T7. Since the time interval between any two consecutive "snapshot" times is equal to T in equation (1), the switching times are equal to (T1+ T2)/2, (T2+ T3)/2, (T3+ T4)/2, (T4+ T5)/2, (T5+ T6)/2 and (T6+ T7)/2, respectively. Because the dose is additive, the resulting dose distribution along line AB will have the same shape as the resulting dose distribution 1401 in FIG. 14. Fig. 15 shows a total dose distribution 1501. The following is shown in figure 15: total dose distribution 1501, 50% dose marks 1504, 50% position marks 1505, exposed regions 1506, unexposed regions 1507, and projected line pitch 1215. The total dose is preferably adjusted so that the edge of the printed feature is on 50% of the location marks 1505 after development. In that case, the area with a total dose greater than 50% is the exposed area 1506, while the area with a total dose less than 50% is the unexposed area 1507. Under these conditions, the final developed pattern will be similar to the resulting image 1007 in fig. 10 — the bright areas correspond to exposed areas 1506 and the dark areas correspond to unexposed areas 1507. All patterned edges are in line with the reference grid except for some corner rounding. Slight variations in exposure dose will affect the vertical and horizontal dimensions differently. This is a practical problem only if the slope of the light intensity distribution at and around 50% of the light intensity distribution is not steep enough (steep slope allows for sufficient linear width control, assuming reasonable exposure and process variations).

Consider the lithography tool of fig. 1 and 10 as described above. The dose distribution in the x-direction over the surface of the substrate is given by:

where N is a constant, Iw (x, T) is the time-dependent light intensity distribution on the surface of the substrate, and time T satisfies equation (1). If the substrate is moving at a constant velocity v, the light intensity Iw of the moving substrate is related to the light intensity I for the stationary substrate by:

Iw(x，t)＝I(x+vt，t) (3)

between T0 and T/2, the elements in the SLM are in one state and are shifted by one row at T/2, i.e.:

I(x，t)＝I₀(x) 0＜t＜T/2

I(x，t)＝I₀(x-pM) T/2＜t＜T (4)

here I₀(x) Is the intensity distribution for a single SLM element with a stationary substrate, p is the row pitch of the SLM array elements, and M is the projection lens system magnification factor. Using equations (1), (3), and (4), equation (2) can be written as:

as an example, assume distribution I₀(x) Is a gaussian function. Then for 10 rows of elements in the "on" state, the intensity distribution in the substrate will be:

where σ is²Is the variance.

Equations (5) and (6) are examples of forms of equations for calculating the dose distribution and intensity distribution in the drawings.

To make fine adjustments to the position of the feature edges, a "grayscale" technique may be used. When implementing this technique in a device such as the one shown in fig. 1 to 6, it is required that the image of a single element of the SLM manufactured by the projection lens system must be "blurred", i.e. the elements cannot be clearly resolved. This "blurring" can be achieved in a variety of ways, including defocusing, using a microlens array or diffuser, or more generally, by adjusting the numerical aperture of one lens in the projection lens system to reduce the resolution to the desired value. The preferred method is defocusing. This technique can be understood by reference to fig. 6.

FIGS. 16 through 19 show examples of "gray scale" edge translation on the patterned edge orthogonal to the direction of substrate motion during exposure; in these examples, it is assumed that the substrate is moving in the same direction at a constant speed during exposure. Figures 16 to 19 are very similar to figure 10. The main difference is that the trailing edge of the resulting image is staggered by a fraction of the pixels; for example, inspection of the "trailing edge" of the resulting image 1600 in FIG. 16 shows a shift 1601 of 0.5 of the row pitch 1008. Note that the pattern shown on substrate array 1002 does not show any blurring or optical interference effects for ease of illustration.

In FIG. 16, the sequence of the patterning on the SLM array 1000 is the same as the patterning shown in FIG. 10 at times T1, T2, T3, T4, and T6. However, at time T5, the elements in the SLM array 1000 at positions R3C2, R3C3, R3C4, and R3C5 are in the "on" state in FIG. 16 and in the "off" state in FIG. 10. Further, elements in the SLM array 1000 at positions R1C2, R1C3, R1C4, and R1C5 at time T7 are in the "on" state in FIG. 16 and in the "off" state in FIG. 10. Referring to the substrate portion 1002 in fig. 16, pixels R4C2, R4C3, R4C4, and R4C5 are exposed at times T5 and T7, but are not exposed at times T1, T2, T3, T4, or T6. All other rows of the pattern are exposed over four time periods — for example, pixels R1C4 and R1C5 are exposed at times T1, T2, T3, and T4, while pixels R2C2, R2C3, R2C4, and R2C5 are exposed at times T2, T3, T4, and T5. The result of only two time period exposures in row R4 is an edge shift 1601 of approximately 0.5 times the width of the projected row pitch 1008, as can be seen in the resulting image 1600.

As seen in the resulting image 1600, the exposure sequence in fig. 17 produces an edge shift of approximately 0.5 times the width of the projected line pitch 1008. This resultant image 1700 is the same as the resultant image 1600 in FIG. 16; however, the two resulting images are formed with different sets of exposure patterns. The exposure patterns in the 2 drawings are different at times T4, T5, T6, and T7. These 2 examples are certainly not exhaustive. Other sequences of exposure patterns can be devised that can yield the same resulting image.

Fig. 18 shows a further example of "gray level" edge translation, in this example the trailing edge shift 1801 is 0.25 times the row pitch 1008. The patterning sequence on the SLM array 1000 shown in FIGS. 10 and 18 is the same at times T1, T2, T3, T4, T6, and T7. However, the elements in the SLM array 1000 at times T5 at locations R3C2, R3C3, R3C4, and R3C5 are in the "on" state in FIG. 18 and in the "off" state in FIG. 10. Referring to the substrate portion 1002 in fig. 18, pixels R4C2, R4C3, R4C4, and R4C5 are exposed at time T5, but are not exposed at times T1, T2, T3, T4, T6, or T7. All other rows of the pattern are exposed over four time periods. The result of one time period exposure in line R4 at time T5 is an edge shift 1801 that produces a width of approximately 0.5 times the projected line pitch 1008, as shown in the resulting image 1800.

Fig. 19 shows a further example of "gray level" edge translation, in this example the trailing edge shift 1901 is 0.75 times the row pitch 1008. The patterning sequence on the SLM array 1000 shown in FIGS. 19 and 10 is the same at times T1, T2, T3, and T4. However, the elements in the SLM array 1000 at times T5 at locations R3C2, R3C3, R3C4, and R3C5 are in the "on" state in FIG. 19 and in the "off" state in FIG. 10. The elements in the SLM array 1000 at times T6 at locations R2C2, R2C3, R2C4, and R2C5 are in the "on" state in FIG. 19 and in the "off" state in FIG. 10. Further, the elements in the SLM array 1000 at the positions R1C2, R1C3, R1C4, and R1C5 at time T7 are in the "on" state in FIG. 19 and in the "off" state in FIG. 10. Referring to the substrate portion 1002 in fig. 19, pixels R4C2, R4C3, R4C4, and R4C5 are exposed at times T5, T6, and T7, but are not exposed at times T1, T2, T3, or T4. All other rows of the pattern are exposed over four time periods. The result of one time period exposure in row R4 at times T5, T6, and T7 is an edge shift 1901 that produces a width of approximately 0.75 times the projected row pitch 1008, as shown in the result image 1900.

FIG. 20 shows an example of "gray scale" edge translation on a patterned edge parallel to the direction of the substrate during exposure; in this example, it is assumed that the substrate moves in the same direction at a constant speed during exposure. Fig. 20 is very similar to fig. 10. The main difference is that the edges of the resulting image are shifted by a fraction of a pixel; for example, inspection of the edges of the resulting image 2000 shown in fig. 20 shows a shift 2001 of 0.25 times the column pitch 2003.

In FIG. 20, the sequence of patterning on the SLM array 1000 shown in FIG. 20 at times T1, T2, T4, T5, T6, and T7 is the same. However, at time T3, the elements in the SLM array 1000 at positions R2C6, R3C6, and R4C6 are in the "on" state in FIG. 20 and in the "off" state in FIG. 10. Referring to the substrate portion 1002 in FIG. 20, pixels R1C6, R2C6, and R3C6 are exposed at time T3, but not exposed at times T1, T2, T4, T5, T6, or T7. All of its pixels on the substrate array 1002 are exposed over four time periods. The result of one time period exposure in row C6 at time T3 is an edge shift 2001 producing a width of about 0.25 times the projected column pitch 2003 as shown in the resulting image 2000.

Further edge shifting, the exposure of one or more pixels using the corner figures will affect the degree of corner rounding. For example, referring to the result image 1007 in FIG. 10, the exposure at R1C1 or at both R1C2 and R2C1 will change the corner rounding at position R2C 2.

The edge shifts shown in the resulting images of fig. 16 to 20 are only approximate; the actual shift depends on the detailed shape of the instantaneous light intensity distribution on the edge of the exposure pattern. A more accurate determination can be made by using a slightly modified form of equation (5) for the dose distribution, including the light intensity distribution appropriate for the state of the mirror portion for each half cycle of the 7 time periods. For the exposure pattern examples given in fig. 10, 16, 17, 18, and 19, this modified portion of equation (5) can be used to calculate the resulting dose distribution at locations along line AB on substrate array 1002 (see fig. 11). In these calculations, the instantaneous light intensity distribution is assumed to have a gaussian distribution with a σ value of 0.43. These resulting dose profiles are shown in figure 21.

In fig. 21, the resulting dose distributions 2101, 2102, 2103 and 2104 correspond to fig. 10, 16, 18 and 19, respectively; the resulting dose distribution 2102 also corresponds to fig. 17. 50% of the position markers 2105, 2106, 2107, 2108 are used for dose distributions 2101, 2102, 2103 and 2104, respectively. Referring also to the result images in fig. 10, 16, 18 and 19, the regions between-1 and 0 and between 0 and 1 in fig. 21 correspond to R4 and R3, respectively, in the result images. The position markers 2105 for 50% of the calculated dose distribution 2101 are used for the example given in fig. 10 and they cross the abscissa at 0. This result is consistent with the result image 1007 shown in fig. 10. The position markers 2106 of 50% of the calculated dose distribution 2102 are used for the example given in fig. 16, and they cross the abscissa at-0.5. This result is consistent with edge shift 1601. The position markers 2107 for 50% of the resulting dose distribution 2103 were calculated for the example given in figure 18 and they crossed the abscissa at-0.20. This result is slightly different from the 0.25 edge shift 1801 value. The position markers 2108 of 50% of the calculated dose distribution 2104 are used for the example given in fig. 19, and they cross the abscissa at-0.80. This result is slightly different from the 0.75 edge shift 1901 value.

It should be noted that the examples given above are simple and ignore the influence of interference from adjacent elements of the SLM, the strictly correct shape of the light intensity distribution and the limited contrast of the photosensitive substrate. Generally, the correct dose for a particular rim shift needs to be determined experimentally. However, once the relationship between dose and edge shift is determined, this technique can be used to compensate for substrate misalignment and distortion, distortion and aberrations in the projection lens system, and non-uniform illumination. This technique can be used to relax the technical requirements on the optics and thus reduce the cost of the optics.

A preferred SLM device is the binary DMD produced by Texas integers, which has a rectangular array of mirrors-1024 mirrors wide and 768 mirrors deep. The scan direction during exposure of the substrate is preferably orthogonal to the 1024 width direction to minimize the number of times the stage must reverse along its spiral path (see fig. 8). Since the array is 768 lines deep, the exposure pattern will be rolled across the array on 768 different platforms, and there will be 768 opportunities to adjust the edge position if the "grayscale" technique outlined above is used. For the edge placement resolution of 1/768, this will allow the size of the projected line pitch of the DMD in the resulting image. In practice, it rarely exceeds 1/32. Thus, 32 equally spaced edge positions can be selected and super resolution can be used to compensate for non-uniform illumination of the substrate.

The characteristics of the printable substrate subjected to the minimum feature size depend on the light intensity distribution. This will be explained with reference to fig. 22 to 27.

FIG. 22 shows another example of patterning of an SLM on a substrate and corresponding translation of an image. As in the previous example, the substrate is moved over a stage and in the x-direction at a constant speed during exposure. Referring also to fig. 1, the following components are shown: a portion of the SLM120, which is an array 2200 of elements having an area of 5 rows by 6 columns; a corresponding portion of the substrate 140, which is an array 2202 of pixels having an area of 5 rows by 6 columns; resulting image 2207 with projected line pitch (width of pixel) 1008. "snapshots" of corresponding portions of the SLM and the substrate are shown at equally spaced times T1 through T8, where the time intervals satisfy equation (1). This figure is similar to figure 10.

FIG. 23 shows a substrate array 2202 with line segments CD, EF, GH, and IJ located at the center of columns C2, C3, C4, and C5. The light intensity and resulting dose distribution on the surface of the substrate array at the locations indicated by the line segments is determined. Note that the line segments are positioned so that they intersect both the "trailing edge" and the "leading edge" of the exposure pattern in fig. 22.

Fig. 24 shows the resulting dose distribution of the exposed substrate 2202 as shown in detail in fig. 22. A gaussian shape with a value of 0.43 is assumed to be used to derive a transient light intensity distribution of the resulting dose distribution. The following is shown in FIG. 24: the resulting dose distributions 2400, 2401, 2402 and 2403 along the segments CD, EF, GH and IJ, respectively; position markers 2405, 2406, and 2407 corresponding to 50% of dose distributions 2401, 2402, and 2403, respectively; position markers 2404 and 2408 corresponding to 50% of dose distribution 2400; and a projected line pitch 1215. Note that the line segment CD is shown as extending from-2 to 6 on the abscissa; the line segments EF, GH and IJ extend over the same value on the abscissa but are not shown to avoid cluttering the drawing. The regions between-1 and 0, 0 and 1, 1 and 2, 2 and 3, and 3 and 4 on the abscissa in fig. 24 correspond to R5, R4, R3, R2, and R1 in the resultant image 2207 in fig. 22, respectively. If the total dose is adjusted so that the edges of the printed features are at the preferred 50% position mark, the resulting pattern will be similar to the resulting image 2207 in FIG. 22. It should be noted that the resulting dose distribution 2400 in fig. 24 is never higher than about 70% of the dose distributions 2404 and 2403, and the distance between the position markers 2404 and 2408 at 50% is slightly less than the projected line pitch 1008. Clearly, under these conditions, the minimum feature size is approximately the same as the projected line pitch 1008. The "grayscale" technique described below can be used to adjust the width of such features-for example, reducing the total dose to pixels R4C2 in substrate array 2202 in fig. 22 will reduce the height of the resulting dose distribution 2400, which will reduce the size of the printed feature. However, the feature size changes rapidly with changes in dose near the top of the dose distribution 2400. Furthermore, there is always some noise and uncertainty in the total dose, which will place practical limits on this approach.

FIG. 25 shows a further example of the translation of an SLM and corresponding patterning of an image on a substrate. As in the previous example, the substrate is moved over a stage and in the x-direction at a constant speed during exposure. In fig. 25, an example of "gray scale" edge translation over various feature sizes is shown, where the translated edge is orthogonal to the direction of substrate motion during exposure. Referring also to fig. 1, the following components are shown: a portion of the SLM120, which is an array 1000 of elements having an area of 4 rows by 6 columns; a corresponding portion of the substrate 140, which is an array 1002 of pixels having an area of 4 rows by 6 columns; resulting image 2507 having projected line pitch (width of pixel) 1008. "snapshots" of corresponding portions of the SLM and the substrate are shown at equally spaced times T1 through T7, where the time intervals satisfy equation (1). This figure is similar to figure 10.

FIG. 26 shows a substrate array 1002 of line segments KL, MN, OP, QR, and ST located at the centers of columns C2, C3, C4, C5, and C6. The light intensity and resulting dose distribution on the surface of the substrate array at the locations indicated by the line segments is determined. Note that the line segments are positioned so that they intersect both the "trailing edge" and the "leading edge" of the exposure pattern in fig. 25.

FIG. 27 shows the resulting dose distribution of the exposed substrate 1002, as shown in detail in FIG. 25. A gaussian shape with a value of 0.43 is assumed to be used to derive a transient light intensity distribution of the resulting dose distribution. Fig. 27 shows the following: the resulting dose distributions 2700, 2701, 2702, 2703, and 2704 along the line segments KL, MN, OP, QR, and ST; both corresponding to position markers 2710 and 2716 of 50% of dose distribution 2704; both corresponding to position markers 2710 and 2713 of 50% of dose distribution 2703; both corresponding to position markers 2711 and 2714 of 50% of dose distribution 2702; both corresponding to position markers 2712 and 2715 of 50% of dose distribution 2701; and a projected line pitch 1215. Note that the line segment KL is shown extending from-2 to 5 on the abscissa; the line segments MN, OP, QR and ST extend over the same value on the abscissa but are not shown to avoid cluttering the drawing. Regions between-1 and 0, 0 and 1, 1 and 2, and 2 and 3 on the abscissa in fig. 27 correspond to R4, R3, R2, and R1 in the resultant image 2507 in fig. 25, respectively. If the total dose is adjusted so that the edges of the printed features are at the preferred 50% position mark, the resulting composition will be similar to the resulting image 2507 in FIG. 25. It should be noted that the resulting dose distribution 2700 in fig. 27 is never higher than about 45% of the dose distribution 2704 and is therefore not printed. The resulting dose distribution 2700 is caused by alternating single adjacent pixels, as can be seen by examining column C2 of substrate portion 1002 at times T2, T3, T4, and T5 in fig. 25. This is in contrast to the example of fig. 22, where a single pixel exposure produces a printed dose distribution. Referring to fig. 25 and 27, as shown, by examining the distance between the position markers 2711 and 2714 at 50% of the resulting dose distribution 2702, the printed features in columns C3, C4, and C5 are all about 1.5 times the projected row pitch 1008 in width. It is shown that the minimum (actual) feature size is about 1.5 times the projection line pitch when the feature is at some arbitrary position relative to the projected SLM element grid; this is in contrast to the minimum feature size of about 1.0 times the projected line pitch of the visible features positioned on the projected SLM element grid-see fig. 22 and 24.

Referring to FIG. 28, a block diagram of a lithography system of the present invention is shown. Design data retained in design data storage 2804 describes that the system should be printed and input to data preparation computer 2805 for conversion to a form suitable for disaggregating electronic device 2807. The data preparation computer 2805 may also modify the data to compensate for previously measured substrate deformation. Substrate alignment system 2803 can be used to measure substrate deformation. The design data is typically in a CAD (computer aided design) format or in a mask standard format such as GDSII. The design data storage device may be one or more tape or disk drives. The data preparation computer may be any general purpose computer such as an IBM PC. After preparing the computer for data, the data is stored in one or more fast disk drives 2806. The preferred form of such data can be understood by reference to the resulting image in figure 19. The entire area of the substrate 140 is divided into small squares with a pitch equal to the enlarged pitch of the SLM120, with the substrate array 1002 providing a small scale example. Each pixel in the array overlying the substrate is assigned a dose value based on the feature pattern and the values of the look-up table. The values of the lookup table are experimentally determined and account for distortions and aberrations of the projection lens system 130 and illumination non-uniformities from the illumination source 110. As an example, a dose value is derived based on the characteristic composition of the resulting image 1900, assuming 32 gray levels, where 31 corresponds to 100% exposure. The following pixels have a dose value of 31:

R1C4，R1C5，R2C2，R2C3，R2C4，R2C5，R3C2，R3C3，R3C4，R3C5

the following pixels have a dose value of 0:

R1C1，R1C2，R1C3，R1C6，R2C1，R2C6，R3C1，R3C6，R4C1，R4C6

based on the desired edge location 1901, the following pixels have intermediate pixel values between 0 and 31:

R4C2，R4C3，R4C4，R4C5

for convenience, we assign a value of 24 to the pixel above. The dose value is then modified using a look-up table to account for distortions, aberrations, and illumination non-uniformities of the system. Because SLMs are preferred, Texas Instruments DMD devices can switch mirror states on every 102 microseconds and have 1024 rows and 768 columns, which means that fast disk drives need to send 1 row of 1024 pixels on every 102 microseconds. 32 gray levels are applied, which is a data rate of about 6.3 megabytes/second. Such data is readily within the capabilities of current disk drive arrays.

Referring again to fig. 28, the alignment of substrate 140 with stage 150 and projection lens system 130 is determined by reflecting substrate alignment system light 2892 off of features on substrate 140 into substrate alignment system 2803. The substrate alignment system is preferably a "machine vision" system that compares any features on the substrate to a previously stored image or ideal image, such as a cross or circle, to find a match. Substrate alignment system light may come from illumination source 110 through SLM120 and projection lens system 130, or from an external light source. After reflecting off the features on the substrate, the light may travel directly to the substrate alignment system, as shown, or may first pass through a projection lens system ("through-lens" alignment). Light reflected off of features on the substrate may also pass through a projection lens system, reflect off of the SLM, and then enter a substrate alignment system. Stage metrology system 2802 receives stage position information, which may be based on a laser interferometer or linear scale, from stage position optical sensor 2891 and sends the information to control computer 2801. The control computer, in turn, sends signals to the stage x, y motors, which then compensate to the correct position. If edge blurring is achieved by defocus (which is the preferred technique), the control computer instructs the platform to compensate in z until the appropriate gap value is achieved. The gap value is measured by a substrate height detector 450 by means of a substrate height detection medium 490, preferably air. Other types of detection techniques such as optical or capacitive may also work. The gap value (defocus) is selected to produce a desired amount of feature edge blur in the image projected into the substrate. The constant used to compensate for this gap needs to compensate for local substrate height variations. Instead of moving the stage in the z-direction, it is also acceptable to move the projection lens system 130 or the SLM120 in the z-direction. Next, the controlling computer instructs the fast disk drive 2806 to send the first row of data to the decomposition electronics 2807, which loads the mirror state data for the first frame into the SLM memory 2808.

To understand the functionality of the decomposition electronics 2807, it is necessary to first understand the requirements of the SLM 120. All mirrors in the SLM switch states simultaneously. The states of all mirrors are determined by the values stored in the SLM memory 2808, respectively. Thus, the requirements for decomposing electronic devices are: it must load the entire SLM memory with new mirror state values in each mirror clock cycle. For Texas integers DMD devices, this is every 102 microseconds. The decomposition electronics must convert the metric of the pixels of each image to a specular state that translates with the moving substrate. How this can be achieved can be illustrated on the basis of the simplified example of fig. 19. For any pixel in the resulting image 1900, 5 dose levels are possible due to the 4 mirror clock cycles used to translate each line through the mirror portion 1000. For example, a pixel R4C2 in the substrate portion 1002 can be exposed to light at times T4, T5, T6, and T7. Any of the 5 possible exposure sequences may be represented by a string of 0 s and 1 s corresponding to the mirror state at 4 exposure times. For example, for R4C2, the string might be 0111. A suitable set of 5 exposure sequences may be:

0000 0001 0011 0111 1111

other possible sequences may also result in the same dose, such as 1000 instead of 0001. This degree of freedom can be used to compensate for illumination non-uniformities of the illumination source 110. The dose levels corresponding to the exposure sequence are defined as 0, 1, 2, 3 and 4. The dose level of all pixels in row 4(R4) of the SLM array 1000 is sent from the fast disk driver 2806 to the resolving electronics driver 2807 before the mirrors switch at time (T4+ T3)/2. The sequence corresponding to each possible dose level is stored in a look-up table in the decomposition electronics. Again using pixel R4C2 as an example, its dose level will be 3, which corresponds to the sequence 0111. Starting at the state shown at T3, the SLM memory 2808 will have a 0 state loaded for the mirrors in the fourth row and second column R4C2 of the substrate array 1000. The resolving electronics loads the SLM memory with the second number in the exposure sequence (1) in the third row and second column R3C2 of the substrate array 1000 when the mirrors are switched to the state shown at T4. The mirror surface switches states at (T5+ T4)/2. After the mirror is switched to the state shown at T5, the resolving electronics loads the SLM memory with the third number in the exposure sequence (1) in the second row and second column R2C2 of the substrate array 1000. The mirror surface switches states at (T6+ T5)/2. After the mirror is switched to the state shown at T6, the resolving electronics loads the SLM memory with the fourth number in the exposure sequence (1) in the first row and second column R1C2 of the substrate array 1000. The mirror surface switches states at (T7+ T6)/2. The principle of operation is the same for the much larger Texas interrupt DMD array. The decomposition electronics must contain a memory large enough to hold the dose level code for each mirror in the SLM and look-up table. The disaggregated electronic device also contains logic to process the bookkeeping. Since all mirror values need to be determined and loaded into the SLM memory in 102 microsecond mirror clock cycles, many mirror values need to be computed in parallel. For example, if 100 nanoseconds are required to compute the next state for a single mirror, then it is clear that the computation of about 800 mirrors needs to be done in parallel.

The control computer 2801 instructs the platform 150 to move to the starting position and accelerate to the correct constant speed. The control computer 2801 also instructs the illumination source 110 to emit the correct intensity of light to match the requirements of the photosensitive substrate 140. This is usually achieved with a variable optical attenuator. Data from stage metrology system 2802 tells the control computer when the substrate is in the correct position to start exposure. Referring again to FIG. 19, at time T1 minus T/2, where T satisfies equation (1), the bottom of substrate array 1002 will be at substrate position 1/2. At this point, the control computer instructs the spatial light modulator to switch all mirrors to the state corresponding to the new value stored in SLM memory 2808. While the control computer 2801 instructs the fast disk drive 2806 to send the next row of data to the decomposition electronics 2807, the decomposition electronics 2807 load the mirror state data for the second frame into the SLM memory. Repeating this process until the edge of the substrate is reached, at which point the control computer instructs the platform to perform a slew; the system is then ready to begin exposure of the next segment of the spiral path as shown in fig. 8. This process is repeated until the entire patterned area of the substrate has been fully exposed.

The method of operation discussed above with reference to FIG. 28 is readily extended to operate a lithography system of the present invention that includes a plurality of arrays of SLM regions.

Certain embodiments of the lithography tool have an SLM with a plurality of area arrays arranged in a plurality of rows, wherein the following applies in its entirety: (1) the rows of the area array are perpendicular to the direction of motion of the projected image of the SLM array on the substrate; (2) the columns of the area array are individually aligned so that the rows of elements in the array are also perpendicular to the direction of motion of the projected image of the SLM array on the substrate; and (3) the location of the area array is staggered from one row to the next. An example of such a structure is shown in figure 29. In FIG. 29, the area array 2910 is arranged in three rows, where the rows are perpendicular to the direction of motion 2950 of the projected image of the SLM array on the substrate (direction 2950 is also the direction in which the patterning data is rolled across the elements of the area array). The configuration of the SLM area array shown in FIG. 29 allows exposure of a substrate without following a spiral path as shown in FIG. 9 (the path in FIG. 9 is appropriate for a single row of SLM area arrays where there are gaps between the arrays). The staggered structure allows gaps between arrays in one row to be covered by arrays in other rows. The example shown in fig. 29 shows overlays without gaps, where the overlays in 3 rows do not overlap; however, some embodiments may have overlap in coverage. In addition, the array of SLM regions within a substantially circular area (indicated by circle 2960 in FIG. 29) takes advantage of imaging optics, which are typically made up of circular components. For example, the images of the 7 SLM arrays in FIG. 29 can be projected onto the substrate simultaneously by a projection lens system comprising a single set of circular lenses.

FIG. 30 shows the lithography tool of FIG. 4 with the addition of mirror 485, light switching mechanism 121, and second SLM beam collector 481. In this example, the optical switching mechanism 121 is a second SLM. Providing a light path for SLM120 from the light source (comprising components 410 to 417) to substrate 140 is represented by ray 170. An optical switching mechanism 121 is positioned in series with the SLM120 in the optical path. In this example, mirror 485 has also been inserted into the optical path to accommodate SLM121 in the position shown. Obviously, many other optical configurations are possible, which are capable of accommodating an optical switching mechanism in the optical path between the light source and the SLM 120. The SLM121 is a mirror array of mirrors with two states (an "on" state where light is reflected towards the SLM120 and an "off state where the mirrors reflect light towards the second SLM beam collector 481). In this example, all other mirrors act as one switch. The discussion of most of the components of the tool in fig. 30 is found in the text description relating to fig. 4. Further explanation of the operation of the tool refers to fig. 31.

In fig. 31, the timing of the switching of SLMs 120 and 121 is shown by waveforms 3120 and 3121, respectively. When the SLM120 is in the "on" state, all elements of the SLM may be "on" or "off," respectively, in other words, the exposure pattern may be mounted on the SLM. When the SLM120 is in the OFF state, all elements of the SLM are "OFF". The same is true for SLM121, except that all elements of SLM121 are "on" when SLM121 is in the "on" state. The SLMs 120 and 121 have the same time interval T between switching, in other words, the same switching frequency; however, T (1-1/n) are shifted out of phase by time shifting them. All elements of both SLMs are turned off at every other time interval. Light may reach the substrate only when both SLMs are in the "on" state, which is every other time interval for time interval T/n. The image projected in this time interval must traverse the surface of the substrate by a projected mirror pitch distance M (which is the same as one pixel length on the substrate surface). This results in a platform velocity v given by:

v＝npM/T (7)

where n is a constant. The time between exposures of the substrate is 2T, in which time the pattern on the SLM120 is translated by 2n rows. N can in principle have any value greater than 1; however, the actual choice for n is typically an integer greater than 1 but less than 10.

FIG. 32 shows the patterning on the SLM and the translation of the image on the substrate. In this example, the substrate is moved over a stage and in the x-direction at a constant speed during exposure. Referring also to fig. 30, the following components are shown: a portion of the SLM120, which is an array 3200 of elements having an area of 12 rows by 6 columns; a corresponding portion of the substrate 140, which is an array 3202 of pixels having an area of 4 rows by 6 columns; resulting image 3207 with projected line pitch (width of pixels) 1008. The resulting image shows one possible latent image on the substrate due to the completion of the entire exposure sequence. "snapshots" of corresponding portions of the SLM and the substrate are shown at evenly spaced times T1 through T7, where the time intervals are T (times T1 through T5 are also labeled for reference in the timing diagram (FIG. 31)). This portion of the SLM and substrate is shown in fig. 32 as M and S, respectively. The SLM array 3200, the substrate array 3202 and the resulting image 3207 are rendered as if looking down in the-z direction of the stationary coordinate system 160 from a position directly above them. For ease of illustration, the SLM and substrate array are shown adjacent to each other in each "snapshot". The projected line pitch 1008 in the resulting image is the line pitch in the SLM array 3200 multiplied by the magnification of the projection lens system 430. However, for ease of illustration, the SLM and substrate array shown in each "snapshot" are the same size and orientation. The grids shown on the arrays 3200 and 3202 and the image 3207 are for reference only. The light squares in 3200 correspond to SLM elements in the "on" state, while the dark squares correspond to SLM elements in the "off state. The bright and dark areas in 3202 correspond to the states of the SLM elements of the "snapshot". The example shown in fig. 32 is n-2. The exposure is done every 2T and it can be seen that the pattern on the SLM array is shifted by 4 rows in this time period. The resulting image is the same as that seen in fig. 10, even though the substrate in fig. 32 is moving at twice the speed during exposure.

The methods described above with reference to fig. 30 and 32 are examples of how to increase substrate throughput without reducing the switching time of the SLM. This is important when the minimum switching time of the SLM has been used, as the throughput of the substrate is further increased. This increase in throughput comes at the cost of more complex lithography tools, including optical switching mechanisms and SLMs with a larger number of rows (to accommodate the 2n row motion between two exposures).

It is apparent that the tool of fig. 30 can be used to implement the gray scale technique as described previously. The tool of fig. 30 may be modified and operated in a number of ways, as described above with reference to the tool of fig. 1 to 6. For example, various image motion mechanisms such as those shown in fig. 2 and 3 may be integrated into the tool of fig. 30.

It is clear that the optical switching mechanism 121 in fig. 30 may be effective at different positions in the optical path before and after the SLM120, as long as appropriate optical adjustments can be made. The optical switching mechanism may be integrated into the light source and may even be an inherent characteristic of the light source (e.g., a pulsed laser). The light switching mechanism may be an SLM, a light barrier, a rotating mirror or any other optical component capable of controlling the passage of light in the light path. Those of ordinary skill in the art will recognize that there are many ways in which these optical switching mechanisms may be incorporated and used in many embodiments of the lithography tool of the present invention. For example, the addition of certain lenses between SLM121 and SLM120 of FIG. 30 can allow the image of the pixels of SLM121 to be focused onto the pixels of SLM120 in a one-to-one correspondence — this allows SLM121 to be used to independently control the passage of light of different blocks of array elements or even the passage of light of a single element.

Consider now the case where the optical switching mechanism can switch faster than the SLM 120. In fig. 33, the timing of the switching of the SLM120 and the optical switching mechanism is shown by waveforms 3320 and 3321, respectively. When the SLM120 is in the "on" state, all elements of the SLM are "on" and "off", respectively, in other words, the exposure pattern can be mounted on the SLM. When the SLM120 is in the "off" state, all elements of the SLM are "off". The pattern on the SLM may be switched at each time interval T. The optical switching mechanism may be configured as a simple two-state "on"/"off" switch. Light can reach the substrate only when both the SLM and the light switching mechanism are in an "on" state. The optical switching mechanism provides a limited time interval T/n for allowing light to reach the substrate. In this time interval the projected image must be moved over the surface of the substrate by the distance pM of the pitch of the projection mirror (which is the same length as one pixel on the surface of the substrate). This yields the platform velocity v given by equation (7). The time between exposures of the substrate is T, in which the pattern on the SLM120 is translated by n rows. N can in principle be any value greater than 1; however, the actual choice of n is usually an integer larger than 1 and smaller than 20, in which case the time interval may be a factor of the so-called switching time interval.

FIG. 34 shows a lithography tool configured with optics that allow projection images from two SLM area arrays 3420 and 3421 to overlap on the substrate surface. The overlapping images can be aligned-pixel to pixel exactly superimposed-if desired. The light source 110 and prisms 3410 to 3413 provide illumination to the two SLM area arrays 3420 and 3421. The light reflected from the SLM area array is combined by prisms 3410 to 3413, if projected onto the photosensitive surface of substrate 140 by imaging optics 3430. Substrate 140 is implemented by stage 150 moving the substrate in the x-y plane of axes 160. The optical configuration of FIG. 34 can be modified to include more SLM area arrays. An example of an optical structure that allows the projected images of three SLM area arrays to be superimposed on the substrate surface is shown in US patent US6,582,080 to Gibbon et al, which is incorporated herein by reference. Those skilled in the art will appreciate that the tool in fig. 34 may be modified along the line of the apparatus shown in fig. 1 to 6, thereby providing further embodiments of the present invention. The apparatus of fig. 34 may operate in a similar manner to that of fig. 30. The operation of the tool is further explained with reference to fig. 35.

In fig. 35, the timings of switching of the area arrays 3420 and 3421 are shown by waveforms 3520 and 3521, respectively. When array 3420 is in the "on" state, all elements of the array are "on" or "off," respectively, in other words, the exposure pattern can be mounted on the array. When array 3420 is in the "off" state, all elements of the array are "off". This is also true for array 3421. Arrays 3420 and 3421 have the same time interval T between switching, in other words, the same switching frequency; however, T (1-1/n) can be made out of phase by time shifting them. All elements of both arrays are turned "off" at every other time interval. Both area arrays are in an "on" state and the double dose of light reaches the substrate at intervals T/n. In this time interval, the projected image must be moved over the surface of the substrate by a distance pM of the pitch of the projection mirror (which is the same length as one pixel on the surface of the substrate). This yields the platform velocity v given by equation (7). The time between double dose exposures of the substrate is 2T, in which time 2T the pattern on the SLM120 is translated by 2n rows. Adjustment of the developing conditions and dose to the photosensitive surface of the substrate can ensure that only those pixels that have received sufficient double dose exposure will form the developed pattern.

It is apparent that the tool of fig. 34 can be used to implement the gray scale technique as described previously. The tool of fig. 34 can be modified and operated in many ways, as described above with reference to the tools of fig. 1-6 and 30. For example, various image motion mechanisms such as those shown in FIGS. 2 and 3 may be integrated into the tool of FIG. 34.

An alternative mode of operation of the lithography tool of FIG. 34 has the area arrays 3420 and 3421 operating in phase. In this case, the velocity of the substrate will be defined by equation (1). This mode of operation may be useful when a single area array is not capable of delivering a sufficiently large dose per unit time.

Referring to fig. 8 and 9, the SLM area array is oriented so that the columns of pixels of the projected image on the substrate are parallel to the direction of motion of the image itself. This results in blurring of the edges of the pixels perpendicular to the direction of motion; however, edges parallel to the direction of motion are not motion blurred. In order to implement a gray scale technique, the edges parallel to the direction of motion must also be blurred. The blurring of the parallel edges can be achieved in a number of ways as described hereinbefore, all of which involve projecting a blurred image of the SLM onto the surface of the substrate. There is an alternative method of achieving blurred edges which can be used with all embodiments of the lithography tool disclosed above (the array of SLM areas is oriented so that the columns of pixels in the projected image on the substrate are not parallel to the direction of motion of the image itself). For example, the columns in the projected image may be at an angle of 45 degrees to the direction of motion, in which case all edges of a square pixel will be blurred equally by the motion alone.

While the present invention has been described with reference to particular embodiments, the description is for illustrative purposes only and is not intended to limit the scope of the invention, which is claimed below.

Claims (79)

1. A lithographic method comprising the steps of:

illuminating a spatial light modulator comprising at least one area array of individually switchable elements;

projecting an image of said spatial light modulator onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate;

switching said elements of said spatial light modulator while moving said image such that pixels on said photosensitive surface receive energy doses sequentially from a plurality of elements of said spatial light modulator, thereby forming a latent image on said surface; and

blurring said image, wherein said blurring achieves sub-pixel resolution feature edge placement.

2. A lithographic method as in claim 1, wherein said blurring comprises defocusing said image.

3. A lithographic method as in claim 1, wherein said blurring is effected by a diffuser disposed between said spatial light modulator and said substrate.

4. A lithographic method as in claim 1, wherein said blurring comprises adjusting a numerical aperture of projection optics disposed between said spatial light modulator and said substrate.

5. A lithographic method as in claim 1, wherein said blurring is performed by a microlens array disposed between said spatial light modulator and said substrate.

6. A lithographic method as in claim 1, wherein said illuminating step comprises successively illuminating said spatial light modulator.

7. A lithographic method as in claim 1, wherein said irradiating step is performed by a lamp system including an arc lamp.

8. A lithographic method as in claim 1, wherein said irradiating step is performed by a laser.

9. A lithographic method as in claim 8, wherein said laser is a continuous laser.

10. A lithographic method as in claim 8, wherein said laser is a quasi-continuous laser.

11. A lithographic method as in claim 1, wherein, in forming said latent image, said projecting step comprises successively projecting said image of said spatial light modulator onto said photosensitive surface of said substrate.

12. A lithographic method as in claim 1, wherein said projecting step is performed by a telecentric projection lens system.

13. A lithographic method as in claim 1, wherein said spatial light modulator comprises at least one digital micromirror device.

14. A lithographic method as in claim 1, wherein said moving step is performed by a stage.

15. A lithographic method as in claim 14, wherein said spatial light modulator is implemented on said platform.

16. A lithographic method as in claim 15, wherein said projection optics is disposed on said stage.

17. A lithographic method as in claim 14, wherein said substrate is placed on said stage.

18. A lithographic method as in claim 1, wherein said substrate is a flexible film substrate.

19. A lithographic method as in claim 18, wherein said moving step is carried out by rotatable spaced axially parallel film rollers around which said flexible film substrate is wound and tensioned therebetween.

20. A lithographic method as in claim 18, wherein said moving step is further performed by a stage on which said spatial light modulator is placed.

21. A lithographic method as in claim 20, wherein projection optics are placed on said stage.

22. A lithographic method as in claim 20, wherein said stage and said substrate are moved in directions orthogonal to each other.

23. A lithography tool for patterning a substrate, comprising:

a spatial light modulator comprising at least one area array of individually switchable elements;

a light source configured to illuminate said spatial light modulator;

imaging optics configured to project the blurred image of the spatial light modulator onto the substrate; and

an image motion mechanism for moving said image over the surface of said substrate.

24. A lithographic tool as in claim 23, wherein said spatial light modulator comprises at least one digital micromirror device.

25. A lithographic tool as in claim 23, wherein said light source is a continuous light source.

26. A lithographic tool as in claim 23, wherein said light source is an arc lamp.

27. A lithographic tool as in claim 23, wherein said light source is a laser.

28. A lithographic tool as in claim 27, wherein said laser is a continuous laser.

29. A lithographic tool as in claim 27, wherein said laser is a quasi-continuous laser.

30. A lithographic tool as in claim 23, wherein said imaging optics is a telecentric projection lens system.

31. A lithographic tool as in claim 23, wherein said imaging optics are configured to form a defocused image of said spatial light modulator.

32. A lithographic tool as in claim 23, wherein said imaging optics comprise a diffuser configured to blur said image of said spatial light modulator.

33. A lithographic tool as in claim 23, wherein said imaging optics has a numerical aperture adjusted to blur said image of said spatial light modulator.

34. A lithographic tool as in claim 23, wherein said imaging optics has a microlens array configured to blur said image of said spatial light modulator.

35. A lithographic tool as in claim 23, wherein said imaging optics comprises a single projection lens system.

36. A lithographic tool as in claim 23, wherein said imaging optics comprises a projection lens system for each of said area arrays.

37. A lithographic tool as in claim 23, wherein said image movement mechanism comprises a stage on which said substrate is carried.

38. A lithographic tool as in claim 23, wherein said image motion mechanism comprises a stage on which said spatial light modulator is carried.

39. A lithographic tool as in claim 38, wherein said imaging optics are disposed on said stage.

40. A lithographic tool as in claim 23, wherein said image movement mechanism comprises rotatable spaced apart axially parallel film rollers around which said substrate is wound and tensioned therebetween.

41. A lithographic tool as in claim 23, further comprising a control computer configured to control switching of said elements of said spatial light modulator while said image is moving over the surface of said substrate.

42. A lithographic tool as in claim 23, further comprising a substrate height measurement system.

43. A lithography tool for patterning a substrate, comprising:

a spatial light modulator comprising a plurality of area arrays of individually switchable elements;

a light source configured to illuminate said spatial light modulator;

a plurality of projection lens systems configured to project the blurred image of said spatial light modulator onto said substrate; and

an image moving mechanism for moving said image over the surface of said substrate;

wherein the number of said area arrays is larger than the number of said projection lens systems.

44. A lithographic tool as in claim 43, wherein the number of said projection lens systems is a factor of the number of said area arrays.

45. A lithographic method for a substrate, comprising the steps of:

disposing a substrate below the spatial light modulator;

illuminating said spatial light modulator, said spatial light modulator being disposed on a stage, said stage being controlled to move in a patterning direction during exposure of said substrate, said spatial light modulator comprising at least one area array of individually switchable elements, said elements having a pitch p measured in said patterning direction;

moving said spatial light modulator in said patterning direction over said substrate with a velocity v;

projecting an image of said spatial light modulator onto said substrate while said spatial light modulator is moving; and

switching the spatial light modulator at times spaced apart by a time interval T p/v while projecting the image such that pixels on the photosensitive surface of the substrate receive energy doses sequentially from a plurality of elements of the spatial light modulator.

46. A lithographic method as in claim 45, wherein said image of said continuously illuminated spatial light modulator is blurred.

47. A photolithography method for a flexible film substrate, comprising the steps of:

moving said flexible film substrate in a patterning direction at a velocity v;

continuously illuminating a spatial light modulator, said spatial light modulator comprising at least one area array of individually switchable elements, said elements having a pitch p measured in said patterning direction;

illuminating said substrate with an image of magnification M of said continuously illuminated spatial light modulator while said spatial light modulator is moving; and

switching said spatial light modulator at times spaced apart by a time interval T pM/v while illuminating said substrate so that pixels on a photosensitive surface of said substrate receive energy doses sequentially from a plurality of elements of said spatial light modulator,

wherein said movement of said substrate is effected by rotatable spaced axially parallel film rollers around which said substrate is wound and tensioned therebetween.

48. A lithographic method as in claim 47, wherein said image of said continuously illuminated spatial light modulator at magnification M is blurred.

49. A lithographic method comprising the steps of:

(a) disposing a substrate below the spatial light modulator;

(b) illuminating said spatial light modulator, said spatial light modulator comprising at least one area array of individually switchable elements;

(c) projecting a blurred image of said spatial light modulator at magnification M onto a photosensitive surface of said substrate;

(d) moving said image over said photosensitive surface in a patterning direction at a velocity v;

(e) switching said spatial light modulator after a time interval of T pM/v while shifting said image, where p is the pitch of said elements measured in said patterning direction; and

(f) repeating step (e) such that pixels on said substrate receive energy doses sequentially from a plurality of elements of said spatial light modulator until a desired latent image is formed on said photosensitive surface.

50. A lithographic method comprising the steps of:

illuminating a spatial light modulator with a light source, said spatial light modulator comprising at least one area array of individually switchable elements;

projecting an image of said spatial light modulator onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate;

switching said elements of the spatial light modulator at time intervals while moving said image;

controlling the passage of light along an optical path from said light source to said spatial light modulator and terminating at said substrate; and

blurring said image, where blurring achieves sub-pixel resolution feature edge placement.

51. A lithographic method as in claim 50, wherein the passage of light is controlled by a light switching mechanism, said mechanism operating at the same frequency as and out of phase with said elements of said spatial light modulator.

52. A lithographic method as in claim 51, wherein all of said elements of said spatial light modulator are in an off state at intervals, and said switching mechanism is in an off state at intervals.

53. A lithographic method as in claim 50, wherein said light is allowed to pass for a time interval that is a part of said switching time interval, said image being shifted by a single pixel length on said substrate surface in said time interval.

54. A lithographic method as in claim 53, wherein said time interval is a factor of said switching time interval.

55. A lithographic method comprising the steps of:

illuminating a spatial light modulator with a light source, said spatial light modulator comprising at least one area array of individually switchable elements;

projecting an image of said spatial light modulator onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate;

switching said elements of the spatial light modulator at time intervals while moving said image; and

controlling the passage of light along an optical path from said light source to said spatial light modulator and terminating at said substrate;

wherein the passage of light is controlled by a light switching mechanism operating at the same frequency as and out of phase with said elements of said spatial light modulator.

56. A lithographic method as in claim 55, wherein all of said elements of said spatial light modulator are in an off state at intervals and said switching mechanism is in an off state at intervals.

57. A lithographic method comprising the steps of:

illuminating a spatial light modulator with a light source, said spatial light modulator comprising at least one area array of individually switchable elements;

projecting an image of said spatial light modulator onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate;

switching elements of said spatial light modulator at time intervals while moving said image; and

controlling the passage of light along an optical path from said light source to said spatial light modulator and terminating at said substrate;

wherein the passage of light is allowed for a time interval being part of said switching time interval during which said image is shifted by a single pixel length over said substrate surface.

58. A lithographic method as in claim 57, wherein said time interval is a factor of said switching time interval.

59. A lithographic method comprising the steps of:

illuminating a spatial light modulator with a light source, said spatial light modulator comprising at least two area arrays of individually switchable elements;

projecting an image of said array of regions onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate;

switching said elements of said area array while moving said image so that pixels on said photosensitive surface receive energy doses sequentially from elements of said spatial light modulator to form a latent image on said surface;

wherein at least two of said projected images of said area array are superimposed on said substrate.

60. A lithographic method according to claim 59, wherein said array of regions having overlapping projected images on said substrate are switched at the same frequency and out of phase with each other.

61. A lithographic method as in claim 59, further comprising blurring said image, wherein said blurring effects sub-pixel resolution feature edge placement.

62. A lithographic method as in claim 59, wherein said superimposed projection images are aligned.

63. A lithography tool for patterning a substrate, comprising:

a spatial light modulator comprising at least one area array of individually switchable elements;

a light source configured to illuminate said spatial light modulator;

imaging optics configured to project the blurred image of the spatial light modulator onto the substrate;

an optical switching mechanism disposed in an optical path from said light source to said spatial light modulator and terminating at said substrate, said optical switching mechanism configured to control the passage of light along said optical path; and

image motion means for moving said image over said surface of said substrate.

64. A lithographic tool as in claim 63, wherein said optical switching mechanism is a second spatial light modulator.

65. A lithographic tool as in claim 63, wherein said optical switching mechanism is a light barrier.

66. A lithographic tool as in claim 63, wherein said optical switching mechanism is integrated with said light source.

67. A lithography tool for patterning a substrate, comprising:

a first spatial light modulator, said first spatial light modulator comprising at least one area array of individually switchable elements;

a light source configured to illuminate said first spatial light modulator;

imaging optics configured to project an image of said first spatial light modulator onto said substrate;

a second spatial light modulator disposed in an optical path from said light source to said first spatial light modulator and terminating at said substrate, said second spatial light modulator being configured to control the passage of light along said optical path; and

image motion means for moving said image over said surface of said substrate.

68. A lithography tool for patterning a substrate, comprising:

a spatial light modulator, said spatial light modulator comprising at least two area arrays of individually switchable elements;

a light source configured to illuminate said array of regions;

imaging optics configured to project images of said area array onto said substrate, at least two of said images of said area array overlapping in registration; and

an image motion mechanism for moving said image over the surface of said substrate.

69. A lithographic method comprising the steps of:

(a) disposing a substrate below the spatial light modulator;

(b) illuminating said spatial light modulator, said spatial light modulator comprising at least one area array of individually switchable elements;

(c) projecting an image of said spatial light modulator at magnification M onto a photosensitive surface of said substrate;

(d) switching said elements of said spatial light modulator at times spaced apart by a time interval T;

(e) moving said image over said photosensitive surface in a patterning direction at a speed v-npM/T while switching said elements, where p is the pitch of said elements measured in said patterning direction and n is an integer; and

(f) controlling the passage of light along an optical path from said light source to said spatial light modulator and ending at said substrate, wherein the passage of light is controlled by a light switching mechanism operating at the same frequency as said elements of said spatial light modulator and shifted by a time offset T (1-1/n) out of phase with said elements of said spatial light modulator.

70. A lithographic method as in claim 69, wherein a pixel on said substrate receives an energy dose sequentially from a plurality of elements of said spatial light modulator until a desired latent image is formed on said photosensitive surface.

71. A lithographic method as in claim 69, further comprising blurring said image of said spatial light modulator.

72. A lithographic method as in claim 69, wherein all of said elements of said spatial light modulator are in an off state at intervals and said switching mechanism is in an off state at intervals.

73. A lithographic method comprising the steps of:

(a) disposing a substrate below the spatial light modulator;

(b) illuminating said spatial light modulator, said spatial light modulator comprising at least one area array of individually switchable elements;

(c) projecting an image of said spatial light modulator at magnification M onto a photosensitive surface of said substrate;

(d) switching said elements of said spatial light modulator at times spaced apart by a time interval T;

(e) moving said image over said photosensitive surface in a patterning direction at a speed v npM/T while switching said elements, wherein p is the pitch of said elements measured in said patterning direction and n is a constant; and

(f) controlling the passage of light along an optical path from said light source to said spatial light modulator and ending at said substrate, wherein the passage of light is controlled by a light switching mechanism, said mechanism being operated to allow the passage of light during a time interval T/n.

74. A lithographic method as in claim 73, further comprising repeating step (f), whereby pixels on said substrate receive energy doses sequentially from a plurality of elements of said spatial light modulator until a desired latent image is formed on said photosensitive surface.

75. A lithographic method as in claim 73, further comprising blurring said image of said spatial light modulator.

76. A lithographic method as in claim 73, wherein said light switching mechanism is operated to allow light to pass through during a time interval T/n during each time interval T.

77. A lithographic method according to claim 73, wherein n is an integer.

78. A lithographic method comprising the steps of:

illuminating a spatial light modulator with a light source, said spatial light modulator comprising at least one area array of individually switchable elements;

projecting an image of said spatial light modulator onto a photosensitive surface of a substrate;

moving said image over said surface of said substrate; and

switching said elements of said spatial light modulator while moving said image;

wherein the direction of motion of said image is not parallel to the columns of pixels in said projected image of said spatial light modulator.

79. A lithographic method as in claim 78, wherein said elements of said spatial light modulator are switched at time intervals such that a pixel on said substrate receives an energy dose sequentially from a plurality of elements of said spatial light modulator until a desired latent image is formed on said photosensitive surface.