Controlling the light source wavelength for selectable phase shifts between pixels in a digital lithography system

Abstract

A digital lithography system can adjust the wavelength of a light source to compensate for tilt errors in a micromirror while maintaining a perpendicular direction for the reflected light. Adjacent pixels can have a phase shift determined by the optical path difference between their respective light rays. This phase shift can be preselected to be any value by generating the corresponding wavelength at the light source based on the optical path difference. To generate a specific wavelength corresponding to a desired phase shift, the light source can produce a plurality of optical components having wavelengths that bracket the wavelength of the selected phase shift. The intensities of these components can then be individually controlled to produce an effect approximating the selected phase shift on the substrate.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Non - Provisional Application No. 17 / 750,751, filed on May 23, 2022, entitled "CONTROLLING LIGHT SOURCE WAVELENGTHS FOR SELECTABLE PHASE SHIFTS BETWEEN PIXELS IN DIGITAL LITHOGRAPHY SYSTEMS", which is incorporated herein by reference.

[0002] This disclosure generally describes a method for generating a pre - selected phase shift between pixels in a digital lithography system. More particularly, this disclosure describes controlling the wavelength output of a light source to produce or approximate the effect of a pre - selected phase shift on a substrate during a lithography process.

Background Art

[0003] Spatial light modulators are often used to impose spatially varying modulation on a light beam. A digital micromirror device (DMD), an example of a spatial light modulator, is used as a reflective digital optical switch in a variety of applications including digital lithography. In the case of digital lithography, a DMD is generally combined with other image - processing components such as memory, a light source, and optical elements, and is used to project a desired pattern onto a photosensitive material on a substrate being processed.

[0004] A DMD generally includes hundreds of thousands of microscopic mirrors ("micromirrors") arranged in a rectangular array. Each micromirror corresponds to a single pixel of the image to be displayed and can be tilted at various angles about a hinge. Depending on the tilt angle of the micromirror, the micromirror is in an "on" or "off" state. In the on state, light is reflected from the DMD to a lens and ultimately the pixel is brightly projected onto the substrate. In the off state, the light is directed elsewhere, such as to a light dump, and the projected pixel appears dark.

[0005] The phase shift between adjacent micromirrors of a DMD affects the resolution and depth of focus of the projected image. Generally, the phase shift between adjacent micromirrors of a DMD is 0 degrees. A DMD having a 0-degree phase shift between adjacent micromirrors is known as a blazed DMD. Blazed DMDs exhibit good resolution and depth of focus, but as the device dimensions get smaller, improved resolution and better depth of focus are required, especially for line spacing. In mask-based lithography, hard phase shift masks have been used to print extremely narrow dark lines. However, hard phase shift masks have limitations due to the design topology.

[0006] Accordingly, there is a need in the art for improved spatial light modulators that increase image resolution and depth of focus, and digital lithography methods for their use. SUMMARY OF THE INVENTION

[0007] In some embodiments, a digital lithography system can include a first spatial light modulator pixel configured to direct a first light beam onto a substrate during a digital lithography process, a second spatial light modulator pixel configured to direct a second light beam onto the substrate during the digital lithography process, and a light source configured to generate the first light beam. The first light beam can include a plurality of components including a first component having a first wavelength that generates a first phase shift greater than a preselected phase shift and a second component having a second wavelength that generates a second phase shift less than the preselected phase shift. The digital lithography system can include a controller configured to control the intensities of the plurality of components to produce an effect on the substrate that approximates the preselected phase shift.

[0008] In some embodiments, a method of adjusting the phase shift between pixels in a digital lithography system can include projecting a first light beam onto a first spatial light modulator pixel. The first spatial light modulator pixel can direct the first light beam onto the substrate during a digital lithography process. The first light beam can include a plurality of components including a first component having a first wavelength that generates a first phase shift greater than a preselected phase shift and a second component having a second wavelength that generates a second phase shift less than the preselected phase shift. The method can also include projecting a second light beam onto a second spatial light modulator pixel. The second spatial light modulator pixel can direct the second light beam onto the substrate during the digital lithography process. The method can also include controlling the intensities of the plurality of components to produce an effect on the substrate that approximates the preselected phase shift.

[0009] In some embodiments, a method of adjusting or selecting a phase shift between pixels in a digital lithography system may include projecting a first light beam onto a first spatial light modulator pixel. The first spatial light modulator pixel may direct the first light beam onto a substrate during a digital lithography process. The method may also include projecting a second light beam onto a second spatial light modulator pixel. The second spatial light modulator pixel may direct the second light beam onto the substrate during the digital lithography process. The second spatial light modulator pixel may be adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels. The method may additionally include controlling the wavelength of the first light beam and / or the wavelength of the second light beam based on an optical path difference between the first light beam and the second light beam to produce a preselected phase shift between the first light beam and the second light beam on the substrate.

[0010] In any embodiment, any and all of the following features may be implemented in any combination without limitation. The second spatial light modulator pixel may be adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels in a digital micromirror device. The first spatial light modulator pixel may include a micromirror that adjusts between an on position that reflects light onto a substrate and an off position that reflects light away from the substrate. The light source may also be configured to generate a second light beam, such that the first light beam and the second light beam originate from the light source. The second light beam may be generated from a different light source, and the controller may be further configured to control the strength of components in the second light beam to correct for a tilt error in the second spatial light modulator pixel that is different from the tilt error in the first spatial light modulator pixel. The light source may include a plurality of groups of laser diodes. A first subset of the plurality of groups of laser diodes may be configured to output approximately a first wavelength, and a second subset of the plurality of groups of laser diodes may be configured to output approximately a second wavelength. The light source may include a homogenizing rod that mixes a first component with a second component to produce a uniform first light beam. The plurality of components may include a plurality of additional components in addition to the first component and the second component. The first wavelength may produce a first phase shift that is approximately 20° greater than a preselected phase shift. The second wavelength may produce a second phase shift that is approximately 10° less than the preselected phase shift. The preselected phase shift may be selectable to be a phase shift between 0° and 359°. Controlling the strength of the plurality of components may include calculating, for each of the plurality of components in a linear combination of the deviation between the first phase shift and the second phase shift from the preselected phase shift, a weight such that the linear combination is approximately zero. The weights in the linear combination may correspond to the strength of the plurality of components.Approximating a preselected phase shift can generate a pattern of light intensity on a substrate that approximates a pattern of light intensity that would exist on the substrate using a single wavelength corresponding to the preselected phase shift. The first phase shift can be calculated from the first wavelength and the optical path difference between the first ray and the second ray. The second spatial light modulator pixel can be adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels in a digital micromirror device, and the second ray can also include a first component and a second component. Controlling the wavelength of the first ray can include switching between different laser diodes that generate light having different wavelengths. Controlling the wavelength of the first ray can include changing the wavelength of the first ray by controlling the temperature of the light source, mechanically changing the cavity of the light source, or electroacoustically changing the cavity of the light source.

[0011] A further understanding of the nature and advantages of the various embodiments can be realized by reference to the remainder of the specification and the drawings, in which like reference numerals are used throughout several of the drawings to refer to like components. In some instances, sub-labels are associated with the reference numerals to indicate one of a plurality of like components. When reference is made to a reference numeral without designation to an existing sub-label, it is intended to refer to all such plurality of like components.

Brief Description of the Drawings

[0012]

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[0013] FIG. 1 is a perspective view of a system 100 for digital lithography, according to some embodiments. System 100 may include a base frame 110, a slab 120, one or more stages 130 (two are shown as an example), and / or a processing device 160. The base frame 110 may be placed on the floor of a manufacturing facility and may support the slab 120. A passive air isolator 112 may be positioned between the base frame 110 and the slab 120. In some embodiments, the slab 120 may include a monolithic piece of granite, and one or more stages 130 may be disposed on the slab 120. A substrate 140 may be supported by each of the one or more stages 130. A plurality of holes (not shown) may be formed in the one or more stages 130 to allow a plurality of lift pins (not shown) to extend therethrough. The lift pins may rise to an extended position to receive the substrate 140 from, for example, one or more transfer robots (not shown). One or more transfer robots may be used to load and unload the substrate 140 from the one or more stages 130.

[0014] The substrate 140 can be made of, for example, glass and can be used as part of a flat panel display. In some embodiments, the substrate 140 can be made of other materials. In some embodiments, the substrate 140 can have a photoresist layer formed thereon. The photoresist can react to radiation and can include positive photoresist or negative photoresist, which means that after a pattern is written into the photoresist, the portions of the photoresist exposed to radiation can be soluble or insoluble, respectively, in a photoresist developer applied to the photoresist. The chemical composition of the photoresist can determine whether the photoresist becomes a positive photoresist or a negative photoresist. For example, the photoresist can include at least one of diazonaphthoquinone, phenol formaldehyde resin, poly(methyl methacrylate), poly(methylglutarimide), and / or SU-8. In this way, a pattern can be created on the surface of the substrate 140 to form an electronic circuit.

[0015] The system 100 can further include a pair of supports 122 and a pair of tracks 124. The pair of supports 122 can be disposed on the slab 120, and the slab 120 and the pair of supports 122 can be formed as a single piece of material. The pair of tracks 124 can be supported by the pair of supports 122, and one or more stages 130 can be movable along the tracks 124 in the X direction. In some embodiments, the pair of tracks 124 can include a pair of parallel magnetic channels. As shown, each track 124 of the pair of tracks 124 can be linear. In some embodiments, the track 124 can have a non-linear shape. An encoder 126 can be coupled to each of the one or more stages 130 to provide location information to a controller (not shown).

[0016] The processing device 160 may include a support 162 and / or a processing unit 164. The support 162 may be disposed on the slab 120 and may include an opening 166 for one or more stages 130 to pass under the processing unit 164. The processing unit 164 may be supported by the support 162. In some embodiments, the processing unit 164 may include a pattern generator configured to expose a photoresist in a photolithography process. In some embodiments, the pattern generator may be configured to perform a maskless lithography process. The processing unit 164 may include a plurality of image projection devices (shown in FIG. 2). In some embodiments, the processing unit 164 may include a plurality of light sources, such as laser diodes. Each image projection device may be disposed in a case 165. The processing device 160 may be used to perform maskless direct patterning.

[0017] During operation, one of the one or more stages 130 can move in the X direction from the loading position shown in FIG. 1 to the processing position. The processing position can refer to one or more positions of the stage 130 when the stage 130 passes under the processing unit 164. During operation, the one or more stages 130 can be lifted by a plurality of air bearings (not shown) that can move along a pair of tracks 124 from the loading position to the processing position. A plurality of vertical guide air bearings (not shown) can be coupled to each of the one or more stages 130 and positioned adjacent to the inner wall 128 of each support 122 to stabilize the movement of the stage 130. Each of the one or more stages 130 can also be movable in the Y direction by moving along the track 150 to process and / or index the substrate 140. Each of the one or more stages 130 can be capable of independent operation and can scan the substrate 140 in one direction and step in the other direction. In some embodiments, when one of the one or more stages 130 is scanning the substrate 140, another of the one or more stages 130 may be unloading the exposed substrate and loading the next substrate to be exposed.

[0018] A measurement system can measure the X and Y lateral position coordinates of each of the one or more stages 130 in real time so that each of the plurality of image projection devices can accurately place the patterns written on the substrate covered with photoresist. The measurement system can also provide real-time measurement of the angular position of each of the one or more stages 130 about the vertical or Z axis. The angular position measurement can be used to keep the angular position constant during scanning by a servo mechanism, or the angular position measurement can be used to apply corrections to the position of the patterns written on the substrate 140 by the image projection device 290 as shown below in FIG. 2. These techniques can be used in any combination and without limitation.

[0019] Figure 2 illustrates a perspective schematic view of the image projection system 270 of the system 100 according to some embodiments. The image projection system may include a spatial light modulator, a focus sensor and / or a camera, and a projection lens. As shown in FIG. 2, the image projection system 270 may include a light source 272, an aperture 274, a lens 276, a frustro-prism assembly 288, one or more digital micromirror devices (DMDs) 280 (one is shown), a light damper 282, a focus sensor and camera 284, and / or a projection lens 286. The frustro-prism assembly 288, the DMD 280, the focus sensor and camera 284, and the projection lens 286 may be part of an image projection device 290. In some embodiments, the light source 272 may include a light emitting diode (LED) or a laser, and the light source 272 may be capable of generating light having a predetermined or adjustable wavelength. For example, the predetermined wavelength may be in the blue or near ultraviolet (UV) range, such as less than about 450 nm. The frustro-prism assembly 288 may include a plurality of reflective surfaces. In one embodiment, the projection lens 286 may include a 6x or 10x objective lens. Other embodiments of the image projection system that may include a spatial light modulator other than one or more DMDs may include fewer or more components in the system as required for that particular spatial light modulator.

[0020] The present disclosure may refer to a DMD as an example of a spatial light modulator. However, other spatial light modulators are also contemplated in the present disclosure. Other spatial light modulators may include, but are not limited to, arrays of liquid crystals such as liquid crystal displays (LCDs) and ferroelectric liquid crystal displays (FLCoS), and arrays of microscopic light emitting devices (micro LEDs). Each spatial light modulator may include an array of spatial light modulator pixels that are switchable between "on" and "off" such that the pattern of spatial light modulator pixels can modulate a light beam to provide a selected level of attenuation. During operation, the spatial light modulator pixels may be controllable such that each pixel can be made brighter, darker, and / or attenuated.

[0021] During operation of the image projection system 270 shown in FIG. 2, a light beam 273 having a wavelength that is pre-determined or adjustable, such as a wavelength in the blue region, can be generated by the light source 272. The light beam 273 can be reflected by the frustrated prism assembly 288 to the DMD 280. As shown in FIG. 3, the DMD can include a plurality of micromirrors, and the number of micromirrors can correspond to the number of pixels to be projected. The plurality of micromirrors can be individually controllable, and each micromirror of the plurality of micromirrors can be in an on position or an off position based on mask data provided to the DMD 280 by a controller (not shown). When the light beam 273 reaches the micromirrors of the DMD 280, the micromirrors in the on position reflect the light beam 273 to the projection lens 286, and in other words, can form a plurality of writing beams. The projection lens 286 can then project the writing beams onto the surface of the substrate 140. The micromirrors in the off position can reflect the light beam 273 to the light dump 282 or another location instead of the surface of the substrate 140.

[0022] FIG. 3 illustrates a DMD380 according to some embodiments. The DMD380 may be used in the image projection device 290 and the system 100 described above. The DMD380 may also be useful in any other system or device that utilizes a DMD. The DMD380 may include a plurality of spatial light modulator pixels, shown as micromirrors 381, disposed in a micromirror array 383. The DMD380 may be used as a spatial light modulator, and the micromirrors 381 may be tilted at various angles such that after reflection, the on-beam is aimed at the center of the image projection device 290 and the reflected angle of the illumination beam on the DMD380 is adjusted so that the image created in the illumination system is centered in the projection system. In one example, the stable position of each micromirror 381 may be plus or minus approximately 12 degrees with an error of approximately ±1.0 degrees with respect to the surface of the micromirror 381. For example, the first tilt position 389 may correspond to +12 ± 1.0 degrees and the second tilt position 391 may correspond to -12.0 ± 1.0 degrees.

[0023] The edges 385 of the micromirrors 381 may be disposed along orthogonal axes such as the X and Y axes. These axes may coincide with similar axes referenced to the substrate 140 or stage coordinate system after taking into account the 90-degree fold introduced by the frustrated prism assembly 288. However, the hinges 387 on the micromirrors 381 are placed on opposite corners of the micromirrors 381 and may cause the micromirrors 381 to pivot about an axis that is 45 degrees with respect to the X and Y axes. As discussed above, these micromirrors 381 may be switched between an on position and an off position by varying the angle of tilt of the micromirrors.

[0024] In some embodiments, the hinge 387 can be oriented diagonally to tilt each of the micromirrors 381 about an axis that is 45 degrees with respect to each of the X and Y axes of each of the micromirrors 381. In other embodiments, the hinge 387 can be oriented parallel to each edge 385 of each of the micromirrors 381 to tilt each of the micromirrors 381 about an axis parallel to each edge 385 of each of the micromirrors 381. In one example, all of the hinges 387 can be oriented diagonally. In another example, all of the hinges 387 can be oriented parallel to each edge 385 of each of the micromirrors 381. In yet another example, a first portion of the hinge 387 can be oriented diagonally and a second portion of the hinge 387 can be oriented parallel to each edge 385 of each of the micromirrors 381.

[0025] In a conventional blazed DMD, the phase shift between adjacent micromirrors can be 0 degrees. The conventional 0-degree phase shift can result in only a slight cancellation. However, the phase shift between adjacent micromirrors 381 of the DMD 380, e.g., between a first micromirror 381a and a second micromirror 381b, can be equal to or about 180 degrees. This configuration is called an anti-blazed DMD. When the phase shift between adjacent spatial light modulator pixels, e.g., between a first micromirror 381a and a second micromirror 381b, is 180 degrees, there is an exact or nearly exact cancellation between adjacent micromirrors 381 and a symmetric brightening between adjacent pixels. In one example, each pair of adjacent micromirrors 381 has a 180-degree phase shift.

[0026] Figure 4A illustrates a pair of adjacent micromirrors that direct light rays towards a substrate, according to some embodiments. In this example, the first micromirror 402 and the second micromirror 404 can be configured in the "on" position to direct light towards the substrate 451 during a digital lithography process. The angle 424 of the first micromirror 402 can be in an ideal position, such as +12.0°. The angle 426 of the second micromirror 404 can be the same as the angle 424 of the first micromirror 402. When these two angles 424, 426 of the adjacent micromirrors 402, 404 are equal to the ideal values, the light rays reflected from the micromirrors 402, 404 can be directly reflected onto the substrate 451 at an angle of 90° with respect to the substrate 451. For example, the first light ray 406 projected from a light source can be reflected from the first micromirror 402 onto the substrate 451 at a right angle. Similarly, the second light ray 408 can also be reflected from the second micromirror 404 onto the substrate 451 at a right angle. When the light rays hit the substrate 451 at a right angle, this results in vertical features and an accurate layout on the substrate 451.

[0027] In addition to ensuring that the light rays are directed at a right angle onto the substrate 451, another important consideration is the optical path difference (OPD) 420 between any two adjacent micromirrors. As shown in FIG. 4, the OPD 420 between the first light ray 406 and the second light ray 408 represents the difference in the total distance that these light rays travel. In particular, it can be assumed that the distance between each of the micromirrors 402, 404 and the substrate 451 is the same. However, the distances from the light sources that generate the light rays 406, 408 are different because the second micromirror is farther away from the light source than the first micromirror. This difference is represented by the OPD 420, which results in a phase shift between the first light ray 406 and the second light ray 408 on the substrate 451.

[0028] FIG. 5 illustrates how an OPD 506 between two adjacent micromirrors can result in a phase shift on a substrate according to some embodiments. The wave representation 502 of the light ray is represented as a sine wave having a wavelength 504. The OPD 506 represents the additional distance that the second light ray 408 travels in FIG. 4A. Assuming that the first light ray 406 and the second light ray 408 are in phase when the first light ray 406 is reflected from the first micromirror 402, the phase shift 508 can be determined by identifying the remainder when the OPD 506 is divided by the wavelength 504. Each wavelength 504 represents a full 360° phase shift (which can be ignored), and the remainder therefore represents the phase shift between the first light ray 406 and the second light ray 408 on the surface of the substrate 451. As will be described in more detail below, a phase shift that can be accurately predicted or selected can provide several benefits in the lithography process.

[0029] FIG. 4B illustrates adjacent micromirrors having an inclination angle different from the ideal inclination angle according to some embodiments. FIG. 4A illustrates micromirrors operating in the “on” position and tilted at a precise 12.0° angle, presenting inclination angles 424, 426, but not all manufactured DMD arrays are this precise. Generally, the accuracy of the inclination angle in a manufactured DMD array can vary by about 1.0°. In order to identify manufactured DMD arrays with a sufficiently high accuracy (e.g., 12.0° ± 0.06°), a batch of manufactured DMD arrays may need to be analyzed to identify which of the manufactured DMD arrays actually fall within the more stringent manufacturing tolerances. This significantly reduces the yield of manufactured DMD arrays that can be used for lithography processes that require extremely precise mirror tilts.

[0030] Figure 4B illustrates the results of micromirrors 402, 404 having non-ideal tilt angles 440, 442. Assuming that the position of the light source remains unchanged, light rays 406, 408 can be reflected from micromirrors 402, 404 such that light rays 406, 408 are no longer perpendicular to substrate 451. This can result in angled sidewalls as light rays 406, 408 enter the photoresist layer on substrate 451 at an angle. Additionally, since the layer on substrate 451 has a non-negligible thickness, the horizontal location where light rays 406, 408 strike substrate 451 can vary depending on the depth of the top layer. Therefore, errors in the tilt angles 440, 442 of micromirrors 402, 404 can cause the reflected light rays 406, 408 to no longer be perpendicular to substrate 451 and can cause errors in the pattern printed on substrate 451.

[0031] Note that the pitch 422 between two adjacent micromirrors 402, 404 can remain relatively constant within a batch of fabricated DMD arrays or between batches thereof. The pitch 422 can be tightly controlled during manufacturing to minimize variations in the distance between micromirrors in the array.

[0032] Figure 4C illustrates how variations in tilt angles 440, 442 can be addressed in some embodiments by changing the angles of light rays 406, 408. When variations in the tilt angles 440, 442 of micromirrors 402, 404 cause the reflected light rays 406, 408 to no longer be perpendicular to substrate 451, the angles at which light rays 406, 408 are projected towards micromirrors 402, 404 can be adjusted to compensate. For example, the position of the light source can be changed relative to the position of micromirrors 402, 404. Changing the position of the light source can, as a result, change the angle of incidence of light rays 406, 408 since light rays 406, 408 are reflected from micromirrors 402, 404. As illustrated in Figure 4C, this position can be adjusted until light rays 406, 408 are reflected such that light rays 406, 408 are again perpendicular to substrate 451.

[0033] Changing the position or angle at which the light source projects light rays 406, 408 can cause the light rays 406, 408 to be perpendicular to the substrate 451 again, which can also cause the OPD to vary between the light rays 406, 408. For example, the OPD 444 in FIG. 4C is shorter than the OPD 420 in FIGS. 4A and 4B. As described above and as illustrated in FIG. 5, changing the OPD 444 can directly affect the phase shift 508 between the light rays 406, 408 on the substrate 451.

[0034] Different phase shifts may be desired for different purposes during the lithography process. For example, a 180° phase shift between adjacent micromirrors can create a null at the boundary line between the two micromirrors. This enables the lithography pattern to create a very high-density line-space pattern where the line plus space pitch is equal to the pitch between two adjacent micromirrors for resolution improvement. In another example, a 0° phase shift between adjacent micromirrors can reinforce the pattern at the boundary. Other pattern designs may benefit from using selectable phase shifts such as 90°, 270°, and / or any other degree of phase shift. Therefore, it may be desirable not only to maintain the selected phase shift to compensate for light source location or tilt angle errors, but also to select any phase shift based on the needs of a particular design.

[0035] To overcome this technical problem, the embodiments described herein may adjust the wavelengths of light rays 406, 408 using various techniques to select or adjust a desired phase shift. Three variables, namely, the pitch 422 between micromirrors 402, 404, the length of the OPD 444, and the wavelengths of light rays 406, 408, may affect the phase shift. Since the pitch 422 may be assumed to be relatively constant and the OPD 444 may vary to maintain perpendicular light rays, some embodiments may adjust the wavelengths of light rays 406, 408 to achieve or finely tune to a preselected phase shift. As illustrated in FIG. 5, adjusting the wavelength 504 for a given OPD 506 adjusts the phase shift 508 in a manner that can be predicted and calculated.

[0036] FIG. 6 illustrates a system 600 for adjusting the phase shift between pixels in a digital lithography system, according to some embodiments. The system 600 may include an array of micromirrors, including a pair of micromirrors illustrated in FIG. 6, simply referred to as a first micromirror 402 and a second micromirror 404 for purposes of distinction. As described above, these micromirrors 402, 404 may be oriented to the "on" position (e.g., approximately 12°) to direct light from a light source 602 towards a substrate 451 for printing a pattern on a layer on the substrate 451, such as a photoresist layer.

[0037] The system may include a light source 602. The light source 602 may include one or more laser diodes or other light sources configured to generate light at a preselected frequency. As described above, the light source 602 may be configured to adjust the wavelength of the light during operation to set or adjust the phase shift based on the ODP444. Such adjustment may be performed by selecting different colors of laser diodes in the light source to be operable at different times. Some embodiments may perform the adjustment to the wavelength by adjusting the temperature of the light source 602 so as to cause the wavelength to increase / decrease. Some embodiments may include a plurality of light sources that may be substituted for the light source 602 to generate wavelengths at different frequencies.

[0038] Some embodiments may include a controller 604. By way of example, FIG. 13 described below may include a computer system that may be used as a controller for operating the light source 602 as part of a lithography system. For example, the controller 604 may include one or more microprocessors or microcontrollers together with one or more non-transitory computer-readable media storing instructions that cause the microprocessor / microcontroller to perform operations for controlling the frequency, operation, timing, etc. of the light source 602.

[0039] Note that only a single light source 602 is illustrated in FIG. 6. This illustration is provided by way of example only and is not limiting. The light source 602 may be composed of a plurality of laser diodes or other light sources. There may also be other light sources for generating light for other micromirrors in the array. Further, the light source 602 may be responsible for generating the light reflected as the first light ray 406 and / or the second light ray 408. For example, the first light ray 406 and the second light ray 408 may be generated from, but not limited to, the same light source 602 or different light sources.

[0040] FIG. 7 illustrates a flowchart 700 of a method for adjusting or selecting a phase shift between pixels in a digital lithography system, according to some embodiments. The method may include projecting a first light beam onto a first spatial light modulator pixel (702). As described above, the first spatial light modulator pixel may include a digital micromirror. The first spatial light modulator pixel may direct the first light beam onto a substrate during a digital lithography process. The method may also include projecting a second light beam onto a second spatial light modulator pixel (704). The second spatial light modulator pixel may also include a digital micromirror or other similar device, and may likewise direct the second light beam onto a substrate during a digital lithography process. The first and second spatial light modulator pixels may be positioned adjacent to each other in an array of pixels. The first and second light beams may be generated from the same light source, or from different light sources such as phase-locked laser diodes or laser diode arrays.

[0041] This method may be used to set or adjust the phase shift between the first and second light beams on the substrate. For example, when referring to a “preselected phase shift,” this refers to a phase shift specifically selected for a particular lithography process between these particular micromirrors. This may be contrasted with simply generating light at a wavelength that results in an OPD based on tilt error using micromirrors, and performing the process with the resulting phase shift. Instead, the preselected phase shift may be determined for the process, and the wavelength of the light from the light source may be adjusted or selected to generate the preselected phase shift.

[0042] Therefore, the method may further include (706) controlling the wavelength of the first light beam and the wavelength of the second light beam based on the optical path difference between the first light beam and the second light beam. The wavelengths may be selected or adjusted to produce a preselected phase shift between the first light beam and the second light beam on the substrate. The wavelengths may be selected based on the OPD as described above with respect to FIG. 5. As described above, the light source may be configured such that the wavelength of the light generated by the light source is adjustable. This adjustment may be performed by activating different light sources, adjusting the operation of the light source, adjusting the temperature of the light source, mechanically adjusting the cavity length of the laser source, electronically acoustically varying the cavity of the light source, activating or substituting an alternative light source to the lithography system, and / or any other method of adjusting or selecting the wavelength of the light to produce the desired phase shift. For example, a first subset of a plurality of laser diodes may be configured to produce a wavelength that causes a 180° phase shift. A second subset of the plurality of laser diodes may be configured to produce a wavelength that causes a 0° phase shift, and another subset of the laser diodes may be configured to produce another wavelength, such as 270°. These subsets may be activated based on preselected wavelengths.

[0043] It should be understood that the specific steps illustrated in FIG. 7 provide a particular method of adjusting or selecting the phase shift between pixels in a digital lithography system according to various embodiments. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments may perform the steps outlined above in a different order. Moreover, the individual steps illustrated in FIG. 7 may include multiple sub-steps that may be performed in various sequences suitable for the individual steps. Additionally, additional steps may be added or removed depending on the particular application. Many variations, modifications, and alternatives are also within the scope of the present disclosure.

[0044] Next, one particular method for adjusting the effective wavelength of a light source used in a lithography process is described. This method involves using a plurality of light sources having different frequencies and adjusting the intensities of these light sources to produce the effect of a phase shift on a substrate.

[0045] FIG. 8 illustrates a light source 800 that can be used in a lithography system according to some embodiments. This light source 800 is provided by way of example only and is not limiting. Other light sources having different groupings and configurations of laser diodes or other similar devices can be used in its place. This light source 800 can include a laser module 802. The laser module 802 can include a plurality of laser diodes. In some embodiments, the laser diodes can be divided into groups, and the groups can include a plurality of matched laser diodes driven by corresponding drive circuit configurations. Each of the groups can be populated with a plurality of laser diodes having similar wavelengths. Note that FIG. 8 illustrates, as a simplified example for clarity only, four groups each consisting of four laser diodes. Any number of laser diodes and groups can be used without limitation, as indicated by the ellipse.

[0046] For the embodiments described below, some of the groups can include laser diodes configured to emit light at wavelengths shorter than a preselected wavelength, and some of the groups can include laser diodes configured to emit light at wavelengths longer than the preselected wavelength. For example, the first group 808 can be driven by the first drive circuit configuration 806 and can be configured to generate light at a higher wavelength, and the second group 838 can be driven by the second drive circuit configuration 833 and can be configured to generate light at a lower wavelength.

[0047] The system may include a controller 804 configured to control the intensities of various groups of laser diodes. For example, the controller 804 may be implemented using a microprocessor, a microcontroller, and / or a computer system as described below with respect to FIG. 13. The controller 804 may cause the intensity of the first group 808 to be higher than the intensity of the second group 838, or vice versa. The controller 804 may calculate appropriate intensities for each group in the laser module 802, as described in detail below.

[0048] Each laser diode in the laser module 802 may be coupled to a corresponding optical fiber 814. These optical fibers may be bundled together and aimed into a homogenizing rod 816 or other form of optical pipe that scrambles the light into a uniform illumination beam that can be projected onto the micromirrors in the array. Therefore, each of the "light rays" described above may include multiple components from different groups of optical laser diodes that generate light at different wavelengths. For example, a first optical component may be generated by a first group 808 of laser diodes at one wavelength, and a second optical component may be generated by a second group 838 of laser diodes at a different wavelength. The output of the homogenizing rod 816 may be the light 818 directed as one or more light rays, as described above. For example, the light 818 may be the source of both the first and second light rays in FIGS. 4A - 4C and elsewhere in the present disclosure.

[0049] FIG. 9 illustrates a system 900 for using a light beam having a plurality of wavelengths bracketing a preselected wavelength, according to some embodiments. System 900 is similar to the system described above, except that light source 911 may be configured to generate a first light beam 406 having at least two different components. For example, the first component may be generated using a laser diode that outputs light at a wavelength higher than the preselected wavelength, where the preselected wavelength corresponds to a desired phase shift between the first light beam 406 and the second light beam 408 on substrate 451. Similarly, the second component may be generated using a laser diode that outputs light at a wavelength lower than the preselected wavelength. Alternatively, the first component and the second component may be characterized based on their corresponding phase shifts relative to the preselected phase shift. The first component may generate a phase shift greater than the preselected phase shift, and the second component may generate a phase shift less than the preselected phase shift. These two components 902, 904 may be mixed together to form the first light beam 406. As described above, light source 911 may also generate a second light beam 408 that is projected onto the second micromirror 404, although this is not explicitly shown in FIG. 9. Alternatively, a second light source (not shown) may generate the second light beam 408.

[0050] The light source 911 may include the controller described above that controls the intensity of the first component 902 and the intensity of the second component 904. It has been discovered that the effect of a preselected phase shift can be approximated by the combined light intensity of two components on the substrate by bracketing the preselected wavelength or phase shift on the substrate with higher and lower wavelengths or phase shifts than the preselected wavelength or phase shift. Further, by adjusting the relative intensity between the first component 902 and the second component 904, the effective phase shift can be tuned or adjusted between the phase shift of the first component 902 and the phase shift of the second component 904 using a weighted combination of phase shifts.

[0051] FIG. 10 illustrates a graph 1000 of the effect of using a light beam having a plurality of optical components bracketing a preselected phase shift, according to some embodiments. In this example, the preselected phase shift is selected as 0°. This corresponds to a preselected wavelength that can be calculated based on the OPD of a particular micromirror array. Therefore, the preselected phase shift and the preselected wavelength can be used interchangeably since they are easily derivable from one another. Curve 1008 illustrates the intensity of light on the surface of the substrate. The vertical axis of graph 1000 represents the intensity of light on the substrate using a normalized scale of arbitrary units. The horizontal axis of graph 1000 represents the location on the substrate in units of microns (μm). The 0 μm location corresponds to the center position between a first micromirror and a second micromirror that may be adjacent in the array. The pitch between these two micromirrors may be approximately 1.26 μm, which approximately corresponds to the peak on the curve in graph 1000. The results of graph 1000 are based on a defocus level of approximately -3 μm.

[0052] Since the light source may not be readily available for a preselected wavelength corresponding to a 0° phase shift, a first component and a second component having a phase shift greater than the preselected phase shift and a phase shift less than the preselected phase shift can be used simultaneously. In this example, the first component corresponding to curve 1004 represents a wavelength that generates a phase shift approximately 10° less than the 0° phase shift (e.g., 350°), and the second component corresponding to curve 1002 represents a wavelength that generates a phase shift approximately 20° greater than the 0° phase shift. Note that these curves are individually different from curve 1008 corresponding to the preselected wavelength that generates the preselected 0° phase shift.

[0053] However, when the first component and the second component are combined to form a light ray reflected from the micromirror, the overall light intensity on the substrate can be made to approximate the effect of the preselected phase shift of the preselected wavelength. For example, the two components can be combined in a linear combination, where the weights assigned to each component correspond to the differences in their corresponding phase shifts with respect to the preselected phase shift. In this implementation, the weights assigned to each component create a linear combination of two components that is approximately equal to zero. For example, a component having a phase shift of -10° with respect to the preselected 0° phase shift can be multiplied by 2 / 3, and a component having a phase shift of +20° with respect to the preselected 0° phase shift can be multiplied by 1 / 3, such that the linear combination of these components becomes approximately equal to zero. These weights can then be used to control the luminance or intensity of each component. For example, the intensity of the component having a -10° phase shift can be approximately twice the intensity of the component having a +20° phase shift. The intensity of each component can be dynamically controlled during operation by the controller described above.

[0054] The coupling of two components when the strength of each component is controlled is shown as curve 1006 in graph 1000. Note that curve 1006 for the coupled components very closely approximates curve 1008 corresponding to the ideal phase shift at a preselected wavelength. This illustrates how the effects of the first and second components can be used to approximate the effects of a preselected phase shift or wavelength on the substrate by controlling the strengths of these components.

[0055] Figure 11 illustrates a graph showing how multiple components can be used to approximate and tune to any preselected wavelength, according to some embodiments. 0° and 180° were described above as exemplary phase shifts, but these embodiments can be readily used to generate any phase shift between any two micromirrors in the array at various defocus levels. By way of example, graph 1100 illustrates approximating a 0° phase shift at a +3μm defocus length, graph 1102 illustrates approximating an 180° phase shift at a 0μm defocus length, graph 1106 illustrates approximating a 90° phase shift at a +3μm defocus length, and graph 1108 illustrates approximating a 280° phase shift at a 0μm defocus length. These graphs illustrate how any phase shift can be approximated using these techniques.

[0056] In these examples, the preselected phase shift or the phase shift or wavelength bracketing the preselected wavelength was selected such that the higher phase shift was approximately 20° greater than the preselected phase shift and the lower phase shift was approximately 10° less than the preselected phase shift. This particular bracketing of the preselected phase shift has been shown to closely approximate the effect of the preselected phase shift, but not all embodiments need to use these particular values. For example, other embodiments may use phase shift values for the first component that are greater between approximately 5° and approximately 10°, greater between approximately 10° and approximately 15°, greater between approximately 15° and approximately 20°, greater between approximately 20° and approximately 25°, greater between approximately 25° and approximately 30°, etc. Similarly, other embodiments may use phase shift values for the second component that are less between approximately 5° and approximately 10°, less between approximately 10° and approximately 15°, less between approximately 15° and approximately 20°, less between approximately 20° and approximately 25°, less between approximately 25° and approximately 30°, etc. Each of these different ranges can be used in different combinations without limitation and has different advantages depending on the particular lithography pattern, laser diode type, photoresist material, and / or other characteristics of the lithography system.

[0057] The system described above may, as a whole, use the same mixture of wavelengths in the laser diode for the DMD. This enables the system to correct for the average error in the mirror tilt angle of each DMD. However, some embodiments may correct for the individual micromirror tilt errors of the DMD array itself as an addition. For example, the individual wavelengths can be mixed and the angle of incidence can be adjusted across the DMD based on the tilt error of each individual micromirror. These embodiments may vary the light source, intensity, and angle of the light to compensate for local variations in the micromirror tilt angle.

[0058] The examples described above illustrate only two components of the light beam as an example. However, other embodiments may use three or more components of the light beam. For example, a preselected phase shift may be bracketed by three, four, five, etc. components having a phase shift greater than and / or less than a predetermined phase shift. The relative luminance of each of these components can be determined using the weighted combination of the optical components described above. In particular, the weights corresponding to the intensities can be calculated such that the weighted combination of the phase shift deviations from the preselected phase shift is approximately zero.

[0059] FIG. 12 illustrates a flowchart 1200 of a method for selecting or adjusting a phase shift between pixels in a digital lithography system according to some embodiments. The method may include projecting a first light beam onto a first spatial light modulator pixel (1202). As described above, the first spatial light modulator pixel may include a digital micromirror. The first spatial light modulator pixel may direct the first light beam onto a substrate during a digital lithography process. The method may also include projecting a second light beam onto a second spatial light modulator pixel (1204). The second spatial light modulator pixel may also include a digital micromirror or other similar device and may likewise direct the second light beam onto a substrate during a digital lithography process. The first and second spatial light modulator pixels may be positioned adjacent to each other in an array of pixels. The first and second light beams may originate from the same light source or from different light sources such as a laser diode or a laser diode array.

[0060] The first light ray may include a plurality of components including a first component having a first wavelength that generates a first phase shift greater than a preselected phase shift. Similarly, the plurality of components may also include a second component having a second wavelength that generates a second phase shift less than the preselected phase shift. The preselected phase shift may correspond to a desired phase shift between light rays reflected by two micromirrors on a substrate. As described above, the plurality of components in the first light ray may include other components in addition to the two specific components described above. The same light source that generates the first light ray may also generate the second light ray, and thus the second light ray may also include these components.

[0061] The method may further include controlling (1206) the strengths of the plurality of components to produce an effect on the substrate that approximates a preselected phase shift. The strength of each component may be controlled based on a linear combination of the deviation of the corresponding phase shift from the preselected phase shift. The weights applied to each of these phase shift deviations in the weighted combination may be calculated such that the linear combination is approximately zero. The weighted combination may include any number of components in the light ray. Approximating the preselected phase shift may produce a pattern of light intensity on the substrate that approximates a pattern of light intensity that would exist using a single wavelength corresponding to the preselected phase shift.

[0062] It should be understood that the specific steps illustrated in FIG. 12 provide a particular method for selecting or adjusting the phase shift between pixels in a digital lithography system according to various embodiments. Other sequences of steps may also be performed according to alternative embodiments. For example, an alternative embodiment may perform the steps outlined above in a different order. Moreover, the individual steps illustrated in FIG. 12 may include multiple sub-steps that may be performed in various sequences suitable for the individual steps. Further, additional steps may be added or removed depending on the particular application. Many variations, modifications, and alternative forms are also within the scope of the present disclosure.

[0063] Each of the methods described herein can be implemented by a computer system. Each step of these methods can be automatically executed by a computer system and / or provided with input / output involving the user. For example, the user can provide input for each step in the method, and each of these inputs can be in response to a specific output that requires such input, where the output is generated by the computer system. Each input can be received in response to the corresponding required output. Further, the input can be received from the user, received from another computer system as a data stream, retrieved from a memory location, retrieved via a network, requested from a web service, etc. Similarly, the output can be provided to the user, provided to another computer system as a data stream, stored in a memory location, sent via a network, provided to a web service, etc. In short, each step of the methods described herein can be implemented by a computer system, with any number of inputs, outputs, and / or requests to and from the computer system, which may or may not involve the user. Steps that do not involve the user can be said to be automatically implemented by a computer system without human intervention. Therefore, in light of the present disclosure, it will be understood that each step of each method described herein can be varied to include inputs and outputs to and from the user or can be automatically performed by a computer system without human intervention where any decisions are made by a processor. Further, some embodiments of each of the methods described herein can be implemented as a set of instructions stored on a tangible, non-transitory storage medium to form a tangible software product.

[0064] FIG. 13 illustrates an exemplary computer system 1300 in which various embodiments may be implemented. System 1300 may be used to implement either the computer systems or controllers described above. For example, system 1300 may be used to implement a controller that controls the intensity of components of light that are projected onto a micromirror and reflected onto a substrate during the lithography process described above. As shown in the figure, computer system 1300 includes a processing unit 1304 that communicates with several peripheral subsystems via a bus subsystem 1302. These peripheral subsystems may include a processing acceleration unit 1306, an I / O subsystem 1308, a storage subsystem 1318, and a communication subsystem 1324. Storage subsystem 1318 includes a tangible computer-readable storage medium 1322 and system memory 1310.

[0065] Bus subsystem 1302 provides a mechanism for enabling the various components and subsystems of computer system 1300 to communicate with one another as intended. Although bus subsystem 1302 is shown schematically as a single bus, alternative embodiments of the bus subsystem may utilize multiple buses. Bus subsystem 1302 may be any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus that uses any of a variety of bus architectures. For example, such architectures may include an Industry Standard Architecture (ISA) bus, a Micro Channel Architecture (MCA) bus, an Extended ISA (EISA) bus, a Video Electronics Standards Association (VESA) local bus, and a Peripheral Component Interconnect (PCI) bus that may be implemented as a mezzanine bus manufactured in accordance with the IEEE P1386.1 standard.

[0066] The processing unit 1304, which can be implemented as one or more integrated circuits (e.g., a conventional microprocessor or microcontroller), controls the operation of the computer system 1300. One or more processors may be included within the processing unit 1304. These processors may include single-core processors or multi-core processors. In some embodiments, the processing unit 1304 is implemented as one or more independent processing units 1332 and / or 1334, and a single or multi-core processor may be included within each processing unit. In other embodiments, the processing unit 1304 may also be implemented as a quad-core processing unit formed by integrating two dual-core processors on a single chip.

[0067] In various embodiments, the processing unit 1304 can execute various programs in response to program code and can maintain multiple programs or processes running simultaneously. At a given time, some or all of the program code to be executed may reside within the processor 1304 and / or within the storage subsystem 1318. Through suitable programming, the processor 1304 can provide the various functionalities described above. The computer system 1300 may optionally include a processing acceleration unit 1306, which can include a digital signal processor (DSP), an application-specific processor, etc.

[0068] The I / O subsystem 1308 may include a user interface input device and a user interface output device. The user interface input device may include a keyboard, a pointing device such as a mouse or trackball, a touchpad or touch screen incorporated in a display, a scroll wheel, a click wheel, a dial, a button, a switch, a keypad, an audio input device having a voice command recognition system, a microphone, and other types of input devices. The user interface input device may include, for example, a motion detection and / or gesture recognition device such as a Microsoft Kinect (registered trademark) motion sensor that enables a user to control and interact with an input device, such as a Microsoft Xbox (registered trademark) 360 game controller, through a natural user interface using gestures and spoken commands. The user interface input device may also include an eye gesture recognition device such as a Google Glass (registered trademark) blink detector that detects eye activity (e.g., a "blink" while taking a photo and / or making a menu selection) from the user and converts the eye gesture into an input to the input device (e.g., Google Glass (registered trademark)). Additionally, the user interface input device may include a voice recognition detection device that enables a user to interact with a voice recognition system (e.g., a Siri (registered trademark) navigator) through voice commands.

[0069] User interface input devices can include, but are not limited to, 3D mice, joysticks or pointing sticks, game pads and graphic tablets, as well as audio / visual devices such as speakers, digital cameras, digital camcorders, portable media players, webcams, image scanners, fingerprint scanners, barcode readers, 3D scanners, 3D printers, laser rangefinders, and eye tracking devices. Additionally, user interface input devices can include medical imaging input devices such as, for example, computed tomography, magnetic resonance imaging, positron emission tomography, and medical ultrasound examination devices. User interface input devices can also include audio input devices such as, for example, MIDI keyboards, digital musical instruments, etc.

[0070] User interface output devices can include, for example, display subsystems, indicator lights, or non-visual displays such as audio output devices. Display subsystems can be flat panel devices such as those using cathode ray tubes (CRTs), liquid crystal displays (LCDs), or plasma displays, projection devices, touchscreens, etc. Generally, the use of the term "output device" is intended to include all conceivable types of devices and mechanisms for outputting information from computer system 1300 to a user or another computer. For example, user interface output devices can include, but are not limited to, monitors, printers, speakers, headphones, automotive navigation systems, plotters, voice output devices, and modems, and various display devices for visually communicating text, graphics, and audio / video information.

[0071] The computer system 1300 may include a storage subsystem 1318 that includes software elements shown as currently residing within system memory 1310. The system memory 1310 may store program instructions that are loadable and executable on the processing unit 1304, as well as data generated during the execution of these programs.

[0072] Depending on the configuration and type of the computer system 1300, the system memory 1310 can be volatile (such as random access memory (RAM)) and / or non-volatile (such as read-only memory (ROM), flash memory, etc.). RAM is generally immediately accessible to the processing unit 1304 and / or contains data and / or program modules that are currently being operated on and executed by the processing unit 1304. In some implementations, the system memory 1310 can include multiple different types of memory, such as static random access memory (SRAM) or dynamic random access memory (DRAM). In some implementations, a basic input / output system (BIOS), which includes basic routines that help transfer information between elements within the computer system 1300, such as during startup, can generally be stored in the ROM. By way of example and not limitation, the system memory 1310 also illustrates an application program 1312, which can include client applications, web browsers, middle-tier applications, relational database management systems (RDBMS), etc., program data 1314, and an operating system 1316. By way of example, the operating system 1316 can include various versions of Microsoft Windows (registered trademark), Apple Macintosh (registered trademark), and / or Linux operating systems, various commercially available UNIX (registered trademark) or UNIX-like operating systems (including, but not limited to, various GNU / Linux operating systems, Google Chrome (registered trademark) OS, etc.), and / or mobile operating systems such as iOS, Windows (registered trademark) Phone, Android (registered trademark) OS, BlackBerry (registered trademark) 10 OS, and Palm (registered trademark) OS.

[0073] The storage subsystem 1318 may also provide a tangible computer-readable storage medium for storing the basic programming and data constructs that provide the functionality of some embodiments. Software (programs, code modules, instructions) that provides the functionality described above may be stored in the storage subsystem 1318 when executed by a processor. These software modules or instructions may be executed by the processing unit 1304. The storage subsystem 1318 may also provide a repository for storing data used in accordance with some embodiments.

[0074] The storage subsystem 1300 may also include a computer-readable storage medium reader 1320, which may be further connected to a computer-readable storage medium 1322. Together with the system memory 1310 and optionally in combination with the system memory 1310, the computer-readable storage medium 1322 may comprehensively represent a storage medium for temporarily and / or more persistently containing, storing, transmitting, and retrieving computer-readable information, in addition to remote, local, fixed, and / or removable storage devices.

[0075] The computer-readable storage medium 1322 that includes the code or portions of code can also include any suitable medium, including storage media and communication media, such as volatile and non-volatile, removable and non-removable media implemented in any method or technology for information storage and / or transmission, without limitation. This can include tangible computer-readable storage media, such as RAM, ROM, electronically erasable programmable ROM (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or other tangible computer-readable media. This can also include non-tangible computer-readable media, such as data signals, data transmissions, or any other medium that can be used to transmit desired information and can be accessed by computing system 1300.

[0076] As an example, computer-readable storage medium 1322 can include a hard disk drive that reads from or writes to a non-removable non-volatile magnetic medium, a magnetic disk drive that reads from or writes to a removable non-volatile magnetic disk, and an optical disk drive that reads from or writes to a removable non-volatile optical disk such as a CD ROM, DVD, and Blu-Ray (registered trademark) disk, or other optical media. Computer-readable storage medium 1322 can include, without limitation, a Zip (registered trademark) drive, a flash memory card, a universal serial bus (USB) flash drive, a secure digital (SD) card, a DVD disk, a digital video tape, and the like. Computer-readable storage medium 1322 can also include a solid state drive (SSD) based on flash memory, a corporate flash drive, a solid state ROM, etc., an SSD based on non-volatile memory, a solid state RAM, a dynamic RAM, a static RAM, a DRAM-based SSD, a magnetic resistance RAM (MRAM) SSD, etc., an SSD based on volatile memory, and a hybrid SSD that uses a combination of a DRAM-based SSD and a flash memory-based SSD. Disk drives and their associated computer-readable media can provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for computer system 1300.

[0077] The communication subsystem 1324 provides an interface to other computer systems and networks. The communication subsystem 1324 serves as an interface for receiving data from other systems to the computer system 1300 and for transmitting data from the computer system 1300 to other systems. For example, the communication subsystem 1324 may enable the computer system 1300 to connect to one or more devices via the Internet. In some embodiments, the communication subsystem 1324 may include radio frequency (RF) transceiver components, a global positioning system (GPS) receiver component, and / or other components for accessing wireless voice and / or data networks (e.g., using cellular phone technology, advanced data network technologies such as 3G, 4G, or EDGE (Enhanced Data rates for GSM Evolution), WiFi (IEEE802.11 family standards), or other mobile communication technologies, or any combination thereof). In some embodiments, the communication subsystem 1324 may provide wired network connectivity (e.g., Ethernet) in addition to or instead of a wireless interface.

[0078] In some embodiments, the communication subsystem 1324 may also receive input communications in the form of structured and / or unstructured data feeds 1326, event streams 1328, event updates 1330, etc., for one or more users who may use the computer system 1300.

[0079] By way of example, the communication subsystem 1324 may be configured to receive in real time data feeds 1326 such as Twitter (registered trademark) feeds, Facebook (registered trademark) updates, web feeds such as Rich Site Summary (RSS) feeds, and / or real-time updates, etc., from one or more third-party information sources from users of social networks and / or other communication services.

[0080] Additionally, communication subsystem 1324 may also be configured to receive data in the form of a continuous data stream, which may include an event stream 1328 of real-time events and / or event updates 1330, which may be continuous or infinite with essentially no explicit end. Examples of applications that generate continuous data may include, for example, sensor data applications, financial tickers, network performance measurement tools (such as network monitoring and traffic management applications), clickstream analysis tools, automotive traffic monitoring, and the like.

[0081] Communication subsystem 1324 may also be configured to output structured and / or unstructured data feeds 1326, event streams 1328, event updates 1330, etc. to one or more databases that may be communicating with one or more streaming data source computers coupled to computer system 1300.

[0082] Computer system 1300 may be one of various types, including a handheld portable device (such as an iPhone® cellular phone, an iPad® computing tablet, a PDA), a wearable device (such as a Google Glass® head-mounted display), a PC, a workstation, a mainframe, a kiosk, a server rack, or any other data processing system.

[0083] Due to the ever-changing nature of computers and networks, the description of computer system 1300 shown in the figures is only as a specific example. Many other configurations with more or fewer components than the systems shown in the figures are possible. For example, customized hardware may also be used, and / or certain elements may be implemented in hardware, firmware, software (including applets), or combinations. Additionally, connections to other computing devices, such as network input / output devices, may be employed. Based on the disclosure and teachings provided herein, other ways and / or methods for implementing various embodiments should be apparent.

[0084] As used herein, the terms "about" or "approximately" or "substantially" may be construed to be within the range that would be expected by one of ordinary skill in the art in light of this specification.

[0085] In the above description, for purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the various embodiments. However, it will be apparent that some embodiments may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form.

[0086] The above description provides only exemplary embodiments and does not limit the scope, applicability, or configuration of the present disclosure. Rather, the above description of the various embodiments provides a possible disclosure for implementing at least one embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of some of the embodiments recited in the appended claims.

[0087] Specific details are given in the above description to provide a complete understanding of the embodiments. However, it should be understood that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may sometimes be shown as components in block diagram form in order not to obscure the embodiments with unnecessary details. In other instances, well-known circuits, processes, algorithms, structures, and techniques may sometimes be shown without unnecessary detail in order to avoid obscuring the embodiments.

[0088] Also, note that individual embodiments may sometimes be described as a process shown as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. A flowchart may sometimes describe the operations as a sequential process, but many of the operations may be performed in parallel or simultaneously. In addition, the order of the operations may be rearranged. A process ends when its operations are completed, but it may have additional steps not included in the figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its end can correspond to the return of the function to the calling function or the main function.

[0089] The term "computer-readable medium" includes, without limitation, portable or fixed storage devices, optical storage devices, wireless channels, and various other media capable of storing, containing, or carrying instructions and / or data. A code segment or machine-executable instruction can represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment can be coupled to another code segment or to a hardware circuit by passing and / or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. can be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

[0090] Furthermore, embodiments can be implemented by hardware, software, firmware, middleware, microcode, a hardware description language, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments for performing the necessary tasks can be stored on a machine-readable medium. The processor can perform the necessary tasks.

[0091] It should be recognized that in the foregoing specification, features have been described with reference to specific embodiments thereof, but not all embodiments are necessarily limited thereto. The various features and aspects of some embodiments can be used individually or in combination. Furthermore, embodiments can be utilized in any number of environments and applications other than those described herein without departing from the broader spirit and scope of this specification. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

[0092] Additionally, for purposes of illustration, the method has been described in a particular order. It should be understood that in alternative embodiments, the method may be performed in a different order than that described. Also, it should be understood that the methods described above may be implemented by hardware components or may be embodied as a sequence of machine-executable instructions that can be used to cause a machine, such as a general or special purpose processor or logic circuits programmed with instructions, to perform the method. These machine-executable instructions may be stored on one or more machine-readable media, such as a CD-ROM or other type of optical disk, a floppy disk, a ROM, a RAM, an EPROM, an EEPROM, a magnetic or optical card, a flash memory, or other type of media suitable for storing electronic instructions. Alternatively, the method may be implemented by a combination of hardware and software.

Claims

1. A first spatial light modulator pixel configured to direct a first light beam onto a substrate during a digital lithography process; A second spatial light modulator pixel configured to direct a second light beam onto the substrate during the digital lithography process; A light source configured to generate the first light beam, wherein the first light beam has A first component having a first wavelength that generates a first phase shift greater than a preselected phase shift; A second component having a second wavelength that generates a second phase shift less than the preselected phase shift; A light source comprising a plurality of components; A controller configured to control the intensities of the plurality of components to produce an effect on the substrate approximating the preselected phase shift; A digital lithography system comprising.

2. The system of claim 1, wherein the second spatial light modulator pixel is adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels in a digital micromirror device.

3. The system of claim 1, wherein the first spatial light modulator pixel comprises a micromirror that adjusts between an on position that reflects light onto the substrate and an off position that reflects light away from the substrate.

4. The system of claim 1, wherein the light source is also configured to generate the second light beam, whereby the first light beam and the second light beam are generated from the light source.

5. The system of claim 1, wherein the second light beam is generated from a different light source, and the controller is further configured to control the intensities of the components in the second light beam to correct for a tilt error in the second spatial light modulator pixel that is different from a tilt error in the first spatial light modulator pixel.

6. The system of claim 1, wherein the light source comprises a plurality of groups of laser diodes, a first subset of the plurality of groups of laser diodes being configured to output approximately the first wavelength, and a second subset of the plurality of groups of laser diodes being configured to output approximately the second wavelength.

7. The system according to claim 1, wherein the light source comprises a homogenizing rod that mixes the first component with the second component to generate a uniform first light beam.

8. The system according to claim 1, wherein the plurality of components comprises a plurality of additional components in addition to the first component and the second component.

9. A method of adjusting a phase shift between pixels in a digital lithography system, the method comprising: projecting a first light beam onto a first spatial light modulator pixel, wherein the first spatial light modulator pixel directs the first light beam onto a substrate during a digital lithography process, and the first light beam is a first component having a first wavelength that generates a first phase shift greater than a preselected phase shift; and a second component having a second wavelength that generates a second phase shift less than the preselected phase shift, projecting a first light beam comprising a plurality of components; projecting a second light beam onto a second spatial light modulator pixel, wherein the second spatial light modulator pixel directs the second light beam onto the substrate during the digital lithography process; controlling the intensities of the plurality of components to produce an effect on the substrate that approximates the preselected phase shift. A method comprising.

10. The method according to claim 9, wherein the first wavelength generates a first phase shift that is approximately 20° greater than the preselected phase shift.

11. The method according to claim 9, wherein the second wavelength generates a second phase shift that is approximately 10° less than the preselected phase shift.

12. The method according to claim 9, wherein the preselected phase shift is selectable to be a phase shift between 0° and 359°.

13. The method according to claim 9, wherein controlling the intensities of the plurality of components comprises calculating, for each of the plurality of components, a weight in a linear combination of the deviation between the first phase shift and the second phase shift from the preselected phase shift such that the linear combination is approximately zero.

14. The method according to claim 13, wherein the weight in the linear combination corresponds to the strength of the plurality of components.

15. The method according to claim 9, wherein approximating the preselected phase shift approximates a pattern of light intensity that would exist on the substrate using a single wavelength corresponding to the preselected phase shift, and generating a pattern of light intensity on the substrate.

16. The method according to claim 9, wherein the first phase shift is calculated from the first wavelength and the optical path difference between the first ray and the second ray.

17. The method according to claim 9, wherein the second spatial light modulator pixel is adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels in a digital micromirror device, and the second ray also comprises the first component and the second component.

18. A method of adjusting or selecting a phase shift between pixels in a digital lithography system, the method comprising: projecting a first ray onto a first spatial light modulator pixel, wherein the first spatial light modulator pixel directs the first ray onto the substrate during a digital lithography process; projecting a second ray onto a second spatial light modulator pixel, wherein the second spatial light modulator pixel directs the second ray onto the substrate during the digital lithography process, and the second spatial light modulator pixel is adjacent to the first spatial light modulator pixel in an array of spatial light modulator pixels; controlling the wavelength of the first ray and / or the wavelength of the second ray based on the optical path difference between the first ray and the second ray to produce a preselected phase shift between the first ray and the second ray on the substrate; and a method.

19. The method according to claim 18, wherein controlling the wavelength of the first ray comprises switching between different laser diodes that generate light having different wavelengths.

20. The method according to claim 18, wherein controlling the wavelength of the first light beam comprises changing the wavelength of the first light beam by controlling the temperature of the light source, mechanically changing the cavity of the light source, or electroacoustically changing the cavity of the light source.

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