Planarization of spin-on film

Abstract

To provide a method for planarizing a substrate.SOLUTION: A method for planarizing a substrate includes: receiving a substrate having microfabricated structures that differ in height across a working surface of the substrate that define a non-planar topography; depositing a first layer that includes a solubility-shifting agent on the working surface of the substrate by spin-on deposition in a non-planar fashion; exposing the first layer to a first pattern of actinic radiation based on the topography; developing the first layer using a predetermined solvent; and depositing a second layer over the working surface of the substrate that has a greater planarity as compared to the first layer prior to developing the first layer. The first pattern of radiation changes a solubility of the first layer such that upper regions of the non-planar topography of the first layer are soluble to the predetermined solvent.SELECTED DRAWING: Figure 1D

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 990,823, filed March 17, 2020, and U.S. Non-Provisional Patent Application No. 17 / 122,898, filed December 15, 2020, which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to semiconductor manufacturing and related processes, including planarization of spin-on films. [Background technology]

[0003] Semiconductor processing involves forming many layers of materials on a semiconductor substrate. Some integration schemes can include 70 or more levels in a design. Each level involves multiple process steps, including the patterning of various films with different shapes and aspect ratios. These patterning processes can result in non-planar topography that can affect the integrity of spin-on films used in standard semiconductor device processing.

[0004] Photoresist is the basic spin-on material used to pattern large portions of semiconductor layers using lithography. It is important to apply a photoresist film uniformly across the wafer because variations in material thickness significantly hinder the critical dimension resolution of the lithography process. However, applying a photoresist film uniformly across topography can be challenging because the mechanisms of the spin-on process create varying thicknesses or coating defects as the resist interacts with features of varying heights / depths. Summary of the Invention [Means for solving the problem]

[0005] According to one embodiment of the present invention, a method of forming a device includes receiving a substrate having microfabricated structures that vary in height relative to one another in a direction perpendicular to a working surface of the substrate such that the microfabricated structures define a non-planar topography across the working surface of the substrate; depositing a first layer on the working surface of the substrate by spin-on deposition, the first layer including a solubility-shifting agent, resulting in a non-planar film; and exposing the first layer to a first pattern of actinic radiation, wherein the first pattern of actinic radiation defines a non-planar topography of the substrate. wherein a first pattern of actinic radiation alters the solubility of a first layer such that an upper region of the non-planar topography of the first layer is soluble in a predetermined solvent and a lower region of the non-planar topography of the first layer is insoluble in the predetermined solvent; developing the first layer using a predetermined solvent such that the soluble portions of the first layer are removed; and depositing a second layer on the working surface of the substrate by spin-on deposition, wherein a top surface of the second layer has greater planarity compared to a top surface of the first layer before developing the first layer.

[0006] According to one embodiment of the present invention, a method of forming a device includes receiving a substrate having a non-planar surface, the substrate having a first side and a second side, the first side having a greater z-height compared to the second side; depositing a first layer on the working side of the substrate by spin-on deposition, the first layer comprising a solubility-shifting agent such that the first layer results in a non-planar film covering both the first side and the second side; and exposing the first layer to a first pattern of actinic radiation, the first pattern of actinic radiation forming a non-planar film on the first side and the second side. The method includes: based on the coordinate position of the second surface, a first pattern of actinic radiation altering the solubility of the first layer such that a portion of the first layer on the first surface is soluble in a predetermined solvent and a portion of the first layer on the second surface is insoluble in the predetermined solvent; developing the first layer using a predetermined solvent such that the soluble portion of the first layer is removed; and depositing a second layer on the working surface of the substrate by spin-on deposition, wherein an upper surface of the second layer has greater uniformity compared to an upper surface of the first layer before developing the first layer.

[0007] According to one embodiment of the present invention, a method of forming a device includes receiving a substrate including a first set of device features and a second set of device features formed across a major surface of the substrate, wherein the first set of device features have a height that is greater than the second set of device features, and wherein a height difference between the first set of device features and the second set of device features forms a non-planar topography across the major surface of the substrate; spin-coating a first intervening layer onto the substrate; exposing the substrate to a first localized pattern of radiation, wherein the first localized pattern of radiation is projected using direct-write lithography; developing the first intervening layer to reduce the height difference between the first set of device features and the second set of device features; and measuring topographic metrics across the major surface of the substrate.

[0008] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions which should be read in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0009] [Figure 1A] 1A-1D illustrate cross-sectional views of a semiconductor device during various stages of fabrication according to one embodiment of the present application, where FIG. [Figure 1B] 1A-1C illustrate cross-sectional views of a semiconductor device during various stages of fabrication, according to one embodiment of the present application, where FIG. 1B shows the device after depositing a first intervening layer and exposing the first intervening layer to a pattern of radiation. [Figure 1C] 1A-1C show cross-sectional views of a semiconductor device during various stages of fabrication according to one embodiment of the present application, where FIG. 1C shows the device after developing the first intervening layer. [Figure 1D] 1A-1D show cross-sectional views of a semiconductor device during various stages of fabrication according to an embodiment of the present application, where FIG. 1D shows the device after coating the material with a second material. [Figure 2]3 is a flowchart of a method for planarizing a working surface of a substrate, according to one embodiment of the present invention. [Figure 3A] 3A-3D show cross-sectional views of a semiconductor device during various stages of fabrication, according to one embodiment of the present application, where FIG. 3A shows the semiconductor device after exposing the second intervening layer to a pattern of radiation. [Figure 3B] 3A-3C show cross-sectional views of a semiconductor device during various stages of fabrication, according to one embodiment of the present application, where FIG. 3B shows the device after developing the second intervening layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] The emergence of the Internet of Things (IoT) has brought about breakthroughs in the unique design and processing of devices, from smart sensors to biotechnology to MEMS. Many of these devices have large topographical geometries that are inherent to their design at the micrometer scale.

[0011] A given topography directly impacts the processing of semiconductor devices, particularly spin-on films. One such film is photoresist, the basic spin-on material used to pattern large portions of semiconductor layers using lithography. During the photoresist coating process, interaction with the topography can create thickness variations across the wafer. These thickness variations can cause problems for subsequent steps in the semiconductor manufacturing process. For example, lithographic imaging is commonly used as part of the process to pattern the surface of semiconductor devices during manufacturing. One example of a lithographic process includes depositing photoresist on a substrate, partially exposing the photoresist through a patterned etching mask, developing the exposed photoresist to define the mask pattern in the photoresist, and then etching the photoresist to form the pattern in the substrate.

[0012] It is important to apply a photoresist film uniformly to a substrate because variations in material thickness significantly hinder the critical dimension resolution of the lithography process. The critical dimension resolution of a pattern of features depends on variations in the height of the photoresist film thickness. Lithography exposure systems are sensitive to changes in focus. As the thickness of the photoresist varies across the surface of the substrate, the integrity of the subsequent pattern of resolved features also varies. Thus, a non-planar layer of photoresist can induce variations in the critical dimensions, thickness, profile, and / or roughness of the pattern of features being imaged. Uniform definition of device feature patterns is typically important because these dimensions affect device performance / yield.

[0013] Embodiments of the present disclosure describe a method for planarizing non-planar surfaces across a substrate for subsequent lithographic patterning.

[0014] Embodiments of the present disclosure include improved techniques for planarizing films deposited on substrates having varied topography. Embodiments of the present disclosure include applying an intervening layer over the substrate and selectively exposing the intervening layer to improve the planarity of the substrate.

[0015] 1A-1D show cross-sectional views of a semiconductor device during various stages of fabrication according to one embodiment of the present application, where FIG. 1A shows a semiconductor device having a non-planar topography, FIG. 1B shows the device after depositing a first intervening layer and exposing the first intervening layer to a pattern of radiation, FIG. 1C shows the device after developing the first intervening layer, and FIG. 1D shows the device after coating the material with a second material.

[0016] 1A, a semiconductor device 100 has a non-planar topography including microfabricated structures. In one or more embodiments, the microfabricated structures may include a structure 104 that defines a recess 106 and a top surface 108 across an active surface of a substrate 102. While this disclosure describes a "recess," it should be understood that other suitable features may be formed in the semiconductor layer, including lines, holes, open areas, trenches, vias, and / or other suitable structures. The structure 104 and the recess 106 may be formed using conventional lithography processes.

[0017] Substrate 102 generally refers to a workpiece that is processed according to embodiments of the present invention. Substrate 102 may include any material portion or structure of a device, particularly a semiconductor or other electronic device, such as a base substrate structure, such as a semiconductor wafer, a reticle, or a layer on or overlying a base substrate structure, such as a thin film. Thus, substrate 102 is not limited to any particular base structure, underlying layer, or overlying layer, whether patterned or not, but rather is intended to include any such layer or base structure, and any combination of layers and / or base structures.

[0018] The substrate 102 may be a bulk substrate such as a bulk silicon substrate, a silicon-on-insulator substrate, or various other semiconductor substrates including a germanium substrate, a silicon carbide substrate, a gallium nitride (GaN) substrate, including GaN on silicon, and a gallium arsenide substrate.

[0019] In one or more embodiments, the microfabricated structures have different heights relative to one another. For example, in one or more embodiments, the recess has a first height 103, and the structure 104 and top surface 108 have a second height 105 in the z-direction. In one or more embodiments, the difference in height of the microfabricated structures relative to one another can be between 10 nm and 100 nm, e.g., greater than 50 nm. In other embodiments, the difference in height can be greater than 5 micrometers, especially for deep openings / trenches. The height (or depth) of each of the microfabricated structures can be measured using scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), or wafer optical scatterometry.

[0020] 1B shows a cross-sectional view of a semiconductor device after a first intervening layer 110 has been deposited over the working surface of the substrate 102 using spin-on deposition. The first intervening layer 110 may include a photosensitive material such as a positive-tone, negative-tone, or hybrid-tone photoresist. In one example, the first intervening layer 110 includes a phenol-formaldehyde resin or a diazonaphthoquinone-based resin. In one or more embodiments, the first intervening layer 110 may include a chemically amplified resist. In another embodiment, the first intervening layer 110 includes a non-chemically amplified resist material such as polymethyl methacrylate (PMMA) or hydrogen silsesquioxane (HSQ).

[0021] A particular material (e.g., first intervening layer 110) is deposited on substrate 102 by spin-on deposition or spin coating. The substrate is then spun at a relatively high speed, e.g., 2000-8000 rpm, such that centrifugal force moves the deposited material toward the edge of substrate 102, thereby coating it. Excess material is shaken off of substrate 102. The thickness of the photoresist is determined by, among other factors, the viscosity of the resist during spinning and the rotation speed of the substrate.

[0022] After spin-on deposition, the photoresist is baked to form the first intervening layer 110. For example, a soft bake process can be used to evaporate residual solvent in the photoresist and densify the photoresist. The soft bake process involves heating the photoresist within a narrow temperature range, for example, between 75°C and 100°C.

[0023] If the substrate 102 includes a non-planar topography of densely packed microfabricated structures, this density can force the deposited material upward and manipulate the mass fraction of the amount of material that fills within the recesses 106. In other words, the deposited material interacts with the non-planar surface of the substrate 102 (e.g., different heights between the microfabricated structures), which causes the deposited material to deposit at different film thicknesses (e.g., different z-heights across the substrate).

[0024] 1B, first intervening layer 110 is deposited using a spin-on deposition process, resulting in a varying thickness across the non-planar surface of substrate 102. In one or more embodiments, first intervening layer 110 may be deposited at a greater thickness in recesses 106 and at a lesser thickness over structures 104 and upper surface 108 (or vice versa). The topography of first intervening layer 110 is merely an example, and the actual variation in topography may vary from deposition to deposition, even for substrates having a similar topography to substrate 102.

[0025] Advantageously, in one or more embodiments, first intervening layer 110 is exposed to a localized radiation pattern prior to forming the micro-fabricated structures to improve planarization of the working surface of substrate 102.

[0026] 1B , the first interposer layer 110 is exposed to a localized pattern of radiation 112. Prior to exposure to radiation 112, the substrate 102 is aligned with a tool that exposes the substrate 102 to the radiation. In various embodiments, the alignment may depend on the stack being patterned. For example, in one embodiment, the metal material at the back end of the lines may be used to align the tool. In another embodiment, optical alignment using alignment marks may be used. In another embodiment, the topography of the first interposer layer 110 may be used to align the substrate 102.

[0027] After aligning the substrate 102 with the tool, the topography of the first intervening layer 110 is measured. The topography of the first intervening layer can be measured using a metrology tool such as an atomic force microscope (AFM), a profilometer, or an optical thickness metrology tool.

[0028] An exposure pattern for the pattern of radiation 112 is then determined based on the topography and color tone of first intervening layer 110. Because the expected topography is determined by the layout, in some embodiments, the exposure pattern can be predetermined. In one or more embodiments, the pattern of radiation 112 is localized such that portions of first intervening layer 110 covering taller / taller microfabricated structures (e.g., structures 104 and top surface 108) are removed, and portions of first intervening layer 110 filling recesses 106 remain after a subsequent development step.

[0029] In one or more embodiments, the pattern of radiation 112 can include actinic radiation, such as ultraviolet radiation, projected using a maskless lithography tool, such as a direct-write lithography tool. In one or more embodiments, the pattern of radiation 112 can be formed using a direct-write lithography method, such as digital light projection (DLP), grating light valve lithography, electron beam lithography, plasmonic lithography, focused ion beam (FIB) lithography, or nanoimprinting. For example, the pattern of radiation 112 can include actinic radiation having a wavelength between 365 nm and 405 nm and can be formed and projected using a direct-write lithography process in a dedicated direct-write machine. A direct-write lithography process projects the radiation exposure pattern using computer-controlled optics instead of using a traditional mask. Traditionally, exposing a substrate to a pattern of radiation requires designing a mask using computer-aided design (CAD) software, constructing the mask, and exposing the substrate through the mask. However, direct write lithography uses computer-controlled optics to project the radiation, which can create a pattern of radiation directly from a CAD file.

[0030] In one or more embodiments, during mass production, first intervening layers 110 deposited on the same substrate may have different topographies. Therefore, individual radiation patterns must be created to planarize the same substrate. Advantageously, as described above, direct-write lithography is a maskless radiation method that allows the pattern of radiation 112 to be digitally programmed. One advantage of this is that an individual mask does not need to be created each time the first intervening layer 110 is exposed, saving process time and manufacturing costs.

[0031] 1B , in one or more embodiments in which first intervening layer 110 is a positive photoresist, the pattern of radiation 112 is localized on structures 104 and top surface 108. In this manner, the portions of first intervening layer 110 covering structures 104 and top surface 108 are soluble in a solvent, such as a developer, while the portions of first intervening layer 110 filling recesses 106 remain insoluble in the solvent.

[0032] In one or more embodiments in which first intervening layer 110 is a negative photoresist, the pattern of radiation 112 is localized on recesses 106. In this manner, the portion of first intervening layer 110 covering the recesses is insoluble in the solvent, while the portion of first intervening layer 110 covering structures 104 and top surface 108 is soluble in the solvent.

[0033] After exposure to actinic radiation, a hard bake process can be performed to stabilize and harden the photoresist, which can be performed at a higher temperature than the soft bake process, for example, 100°C to 150°C.

[0034] FIG. 1C shows the semiconductor device after a portion of the first intervening layer 110 has been removed.

[0035] 1C , a development step is then performed to remove soluble portions of first intervening layer 110 deposited on structure 104 and top surface 108. In one or more embodiments, if first intervening layer 110 is a positive resist, first intervening layer 110 may be removed by exposing it to a developer that may include a phenol-based stripper, acetone, trichloroethylene, or the like. In one or more embodiments, if first intervening layer 110 is a negative resist, first intervening layer 110 may be removed by exposing it to a developer that may include methyl ethyl ketone, methyl isobutyl ketone, or the like.

[0036] Advantageously, in one or more embodiments, a portion of first intervening layer 110 remains within recess 106. One advantage of this is that the remaining portion of first intervening layer 110 reduces the relative height difference between recess 106 and structure 104 and upper surface 108 (i.e., first intervening layer increases first height 103). Thus, the difference between first height 103 and second height 105 is reduced, resulting in an improved topography.

[0037] In various embodiments, after the development step, metrics of the substrate's topography can be measured. Topography metrics can include, for example, the flatness or uniformity of the first intervening layer 110. Topography metrics can be measured using optical metrology techniques. For example, the thickness of the intervening layer 110 can be measured at different locations, or the height of the top surface of the intervening layer 110 can be measured relative to a horizontal plane at different locations. A statistical distribution can then be used to obtain a measure of the flatness or uniformity of the intervening layer 110. Other less commonly used metrics for measuring topography can also include surface techniques, such as measuring the surface roughness of the substrate 102.

[0038] In one or more embodiments, the topographical metrics can be compared to target topographical metrics. In one embodiment, if the measured topographical metrics meet the target topographical metrics, a conventional lithography process can be used to form a subsequent pattern of microstructures on the substrate. In other embodiments, if the topographical metrics do not meet the target topographical metrics, the above-described process can be repeated until the target topographical metrics are met.

[0039] Referring to FIG. 1D , a second material 114 is deposited on the substrate using spin-on deposition. As shown in FIG. 1D , the second material 114 is deposited in a more planar manner than the deposition of the first intervening layer 110. The composition of the second material 114 depends on whether the target topographical metrics were met in a previous step. In one or more embodiments in which the target topographical metrics were met, the second material 114 may comprise a photoresist used in a lithography process to form a subsequent pattern of the microfabricated structure. In one or more embodiments, if the target topographical metrics were not met, the second material 114 may be a second intervening layer comprising the same material as the first intervening layer 110, intended to further planarize the working surface of the substrate 102.

[0040] FIG. 2 is a flowchart illustrating an example of a process flow used to planarize a working surface of a substrate, in accordance with one embodiment of the present invention.

[0041] As shown in block 200 and described with reference to Figure 1A, a substrate 102 having micromachined structures of different heights relative to one another is formed across the working surface of the substrate 102. The height differences between the micromachined structures define a non-planar topography across the working surface of the substrate 102.

[0042] A first intervening layer 110 is then deposited over the substrate using spin-on deposition, as shown in block 202 and described with reference to Figure 1B. The first intervening layer 110 is then exposed to a pattern of radiation 112, as shown in block 204 and described with reference to Figure 1B.

[0043] Further, as shown in block 206 and described with reference to FIG. 1C, the first intervening layer is developed to remove portions of the first intervening layer 110 deposited on the structure 104 and the upper surface 108.

[0044] Advantageously, as described above, removing portions of first intervening layer 110 deposited on higher surfaces while leaving portions of first intervening layer 110 in recesses reduces the relative height between microfabricated structures. One benefit of this is to improve the planarity of the working surface of substrate 102.

[0045] A topographical metric is then measured across the working surface of the substrate 102, as shown in block 208 and described with reference to FIG. 1C . The measured topographical metric is then compared to a target topographical metric, as shown in block 210. In various embodiments, the target topographical metric may be a surface height relative to a horizontal plane measured using optical or electron microscopy techniques. In one or more embodiments, the surface height may be defined based on the tolerance level of the process equipment being used, for example, the depth of focus of a lithography imaging tool. In one or more embodiments, the standard deviation of the surface height of the top surface may be compared to a target standard deviation, and topologies outside the target standard deviation may be marked as failing the topographical metric. In other embodiments, the target topographical measurement may be defined as the uniformity of the first intervening layer 110. The flatness or uniformity of the first intervening layer 110 may be measured using optical metrology techniques. If the measured topographical metrics meet the target topographical metrics, the method proceeds to block 212 where a subsequent pattern of microstructures may be formed on the substrate 102 using conventional lithographic processes.

[0046] If the measured topographical metrics do not meet the target topographical metrics, the method proceeds to block 214 .

[0047] Next, after forming the subsequent pattern of the micro-fabricated device, the topographical metric of the subsequent pattern of the micro-fabricated device is compared to the threshold topographical metric, as shown in block 213. In response to determining that the topographical metric of the subsequent pattern of the micro-fabricated device is greater than the threshold topographical metric, the process proceeds to block 214.

[0048] In contrast, if the topography metric is determined to be less than or equal to the threshold topography metric, the process proceeds to block 216 and standard semiconductor device processing continues.

[0049] Next, as shown in block 214 and described with reference to FIG. 1D , if the target topographical metrics do not meet the measured topographical metrics, an additional intervening layer is deposited on the substrate using spin-on deposition. In one or more embodiments, the additional intervening layer may comprise the same material as first intervening layer 110. After depositing the additional intervening layer, the method repeats blocks 204-212 until the target topographical metrics are met.

[0050] Figures 3A-3B illustrate an example of further planarizing a substrate when the measured topographical metrics do not meet the target topographical metrics. Figures 3A-3C thus continue from Figures 1A-1D.

[0051] 3A-3B are cross-sectional views of a semiconductor device during various stages of fabrication according to one embodiment of the present application, where FIG. 3A shows the semiconductor device after exposing the second intervening layer to a pattern of radiation and FIG. 3B shows the device after developing the second intervening layer.

[0052] Referring to Figure 3A, a second intervening layer 314 is deposited on a substrate using spin-on deposition and exposed to a pattern of radiation 112. As shown in Figure 3A, the second intervening layer 314 is deposited with improved planarity compared to when the first intervening layer 110 was deposited due to a reduction in the relative height difference between the microstructures. In one or more embodiments, the second intervening layer 314 can comprise the same material as the first intervening layer 110. The pattern of radiation can comprise the same material and can be formed in the same manner as described in Figure 1B.

[0053] 3B, second intervening layer 314 undergoes a development step to remove portions of second intervening layer 314 that cover structure 104 and top surface 108. The development step can include the same materials and can be performed in the same manner as described in FIG. 1C.

[0054] 3B, for the reasons discussed above, the relative height difference between recess 106 and structure 104 and upper surface 108 is further reduced by second intervening layer 314. This results in further improved planarization of substrate 102.

[0055] Exemplary embodiments of the present invention are summarized here. Other embodiments may be understood from the entire specification and claims filed herewith.

[0056] Embodiment 1. A method of planarizing a substrate, comprising: receiving a substrate having microfabricated structures that vary in height relative to one another in a direction perpendicular to a working surface of the substrate, such that the microfabricated structures define a non-planar topography across the working surface of the substrate; depositing a first layer on the working surface of the substrate by spin-on deposition, the first layer comprising a solubility-shifting agent, resulting in a non-planar film; and exposing the first layer to a first pattern of actinic radiation, the first pattern of actinic radiation being based on the topography of the substrate; 1. A method comprising: a first pattern of actinic radiation altering the solubility of a first layer such that upper regions of the non-planar topography of the first layer are soluble in a predetermined solvent and lower regions of the non-planar topography of the first layer are insoluble in the predetermined solvent; developing the first layer using the predetermined solvent such that the soluble portions of the first layer are removed; and depositing a second layer on a working surface of a substrate by spin-on deposition, wherein a top surface of the second layer has greater planarity compared to a top surface of the first layer before developing the first layer.

[0057] Embodiment 2. The method of embodiment 1, wherein the first pattern of actinic radiation is projected using a direct write system.

[0058] Embodiment 3. The method of any one of embodiments 1 or 2, wherein the microfabricated structures have a relative height difference of more than 5 micrometers.

[0059] Embodiment 4. The method of any one of embodiments 1-3, wherein the microfabricated structures have a relative height difference of more than 50 nanometers.

[0060] Embodiment 5. The method of any one of embodiments 1-4, wherein the second layer comprises a solubility-shifting agent, further comprising: exposing the second layer to a first pattern of actinic radiation, wherein the first pattern of actinic radiation changes the solubility of the second layer such that an upper region of the second layer is soluble in a predetermined solvent and a lower region of the second layer is insoluble in the predetermined solvent; and developing the second layer using the predetermined solvent, such that the soluble portion of the first layer is removed.

[0061] Embodiment 6. A method of planarizing a substrate, comprising: receiving a substrate having a non-planar surface, the substrate having a first side and a second side, the first side having a greater z-height compared to the second side; depositing a first layer on the working side of the substrate by spin-on deposition, the first layer comprising a solubility-shifting agent, resulting in a non-planar film covering both the first side and the second side; and exposing the first layer to a first pattern of actinic radiation, the first pattern of actinic radiation forming a first pattern of actinic radiation corresponding to coordinates of the first side and the second side. 1. A method comprising: based on the position, a first pattern of actinic radiation altering the solubility of a first layer such that a portion of the first layer on the first surface is soluble in a predetermined solvent and a portion of the first layer on the second surface is insoluble in the predetermined solvent; developing the first layer using a predetermined solvent such that the soluble portion of the first layer is removed; and depositing a second layer on the working surface of the substrate by spin-on deposition, wherein a top surface of the second layer has greater uniformity compared to a top surface of the first layer before developing the first layer.

[0062] Embodiment 7. The method of embodiment 6, wherein the first pattern of actinic radiation is projected using a direct write system.

[0063] Embodiment 8. The method of any one of embodiments 6 or 7, further comprising: exposing the second layer to a first pattern of actinic radiation, the first pattern of actinic radiation being based on coordinate positions of the first surface and the second surface, and the first pattern of actinic radiation altering the solubility of the second layer such that portions of the second layer on the first surface are soluble in a predetermined solvent and portions of the second layer on the second surface are insoluble in the predetermined solvent; and developing the second layer using the predetermined solvent to remove the soluble portions of the second layer.

[0064] Embodiment 9. The method of any one of embodiments 6 to 8, wherein the first surface has a z-height greater than at least 5 micrometers compared to the second surface.

[0065] Embodiment 10. The method of any one of embodiments 6 to 9, wherein the first surface has a z-height that is at least 50 nm greater than the second surface.

[0066] Embodiment 11. The method of any one of embodiments 6 to 10, wherein the first pattern of actinic radiation has a wavelength of 193 nm to 405 nm.

[0067] Embodiment 12. A method of forming a device, comprising: receiving a substrate including a first set of device features and a second set of device features formed across a major surface of the substrate, wherein the first set of device features have a height greater than the second set of device features, and wherein a height difference between the first set of device features and the second set of device features forms a non-planar topography across the major surface of the substrate; spin-coating a first intervening layer onto the substrate; exposing the substrate to a first localized pattern of radiation, wherein the first localized pattern of radiation is projected using direct write lithography; developing the first intervening layer to reduce the height difference between the first set of device features and the second set of device features; and measuring topographic metrics across the major surface of the substrate.

[0068] Embodiment 13. The method of embodiment 12, further comprising: comparing the topography metrics with target topography metrics; and, in response to determining that the topography metrics meet the target topography metrics, forming a subsequent pattern of device features using a conventional lithography process.

[0069] Embodiment 14. The method of any one of embodiments 12 or 13, further comprising: comparing the topographical metric with a target topographical metric; and, in response to determining that the topographical metric differs from the target topographical metric, spin-coating a second intervening layer onto the substrate, exposing the substrate to a first localized pattern of radiation, and developing the second intervening layer to further reduce the height difference between the first set of device features and the second set of device features.

[0070] Embodiment 15. The method of any one of embodiments 12-14, wherein the first intervening layer comprises a positive photoresist, and a localized pattern of radiation is formed on the first set of device features.

[0071] Embodiment 16. The method of any one of embodiments 12-15, wherein the first intervening layer comprises a negative photoresist, and a localized pattern of radiation is formed on the second set of device features.

[0072] Embodiment 17. The method of any one of embodiments 12-16, wherein the first radiation comprises actinic radiation.

[0073] Embodiment 18. The method of any one of embodiments 12 to 17, wherein the first radiation has a wavelength of 193 nm to 405 nm.

[0074] Embodiment 19. The method of any one of embodiments 12 to 18, wherein the height difference between the first set of device features and the second set of device features is greater than 5 micrometers.

[0075] Embodiment 20. The method of any one of embodiments 12 to 19, wherein the height difference between the first set of device features and the second set of device features is greater than 50 nm.

[0076] In the foregoing description, specific details have been set forth, such as the particular geometry of the processing system and descriptions of the various components and processes used therein. However, it should be understood that the technology herein may be practiced in other embodiments that deviate from these specific details, and that such details are for purposes of explanation and not limitation. The embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, for purposes of explanation, specific numbers, materials, and configurations have been set forth to provide a thorough understanding. Nevertheless, embodiments can be practiced without such specific details. Components having substantially the same functional configurations are indicated by similar reference numerals, and therefore any redundant description may be omitted.

[0077] To aid in understanding various embodiments, various techniques have been described as multiple discrete operations. The order of description should not be construed as to imply that these operations are necessarily order dependent. In fact, these operations need not be performed in the order presented. The operations described may be performed in a different order than in the described embodiments. Various additional operations may be performed and / or described operations may be omitted in additional embodiments.

[0078] Those skilled in the art will also appreciate that there may be many variations that can be made to the operation of the techniques described above while still achieving the same objectives of the present invention. Such variations are intended to be encompassed within the scope of the present disclosure. Accordingly, the above description of embodiments of the present invention is not intended to be limiting. Rather, any limitations on embodiments of the present invention are set forth in the following claims.

Claims

1. 1. A method of planarizing a substrate, comprising: receiving a substrate having a non-planar surface, the non-planar surface having at least two first and second surfaces, and a recess defined between the first and second surfaces, the first surface having a z-height that is at least 5 micrometers greater than the second surface; depositing a first layer on the non-planar surface of the substrate by spin-on deposition, the first layer including a solubility-shifting agent, and depositing the first layer results in a non-planar film, the first layer covering both the first surface and the second surface but not completely filling the recess; exposing the first layer to a first pattern of actinic radiation without the use of a mask using a direct write system, the first pattern of actinic radiation being digitally programmed based on coordinate positions of the first surface and the second surface, the first pattern of actinic radiation altering a solubility of the first layer such that portions of the first layer on the first surface are soluble in a predetermined solvent and portions of the first layer on the second surface are insoluble in the predetermined solvent; developing the first layer using the predetermined solvent, wherein soluble portions of the first layer are removed, and the developing step results in a wet-treated upper surface of the substrate; depositing a second layer on the wet-treated top surface of the substrate by spin-on deposition, wherein the top surface of the second layer has a higher uniformity than the top surface of the first layer prior to developing the first layer; exposing the second layer to a first pattern of actinic radiation, the first pattern of actinic radiation being based on coordinate positions of the first surface and the second surface, the first pattern of actinic radiation altering a solubility of the second layer such that portions of the second layer on the first surface are soluble in a predetermined solvent and portions of the second layer on the second surface are insoluble in the predetermined solvent; developing the second layer using the predetermined solvent, whereby soluble portions of the second layer are removed; A method comprising:

2. The method of claim 1 , wherein the first pattern of actinic radiation has a wavelength between 193 nm and 405 nm.

3. 1. A method of forming a device, comprising: The method comprises: receiving a substrate having a non-planar topography across a major surface, the non-planar topography having at least two first surfaces, a second surface, and a recess defined between the first surface and the second surface, the first surface having a z-height that is at least 5 micrometers greater than the second surface; spin-coating a first intervening layer on top of the substrate, the first intervening layer covering both the first surface and the second surface but not completely filling the recess; exposing the substrate with a first localized pattern of radiation, the first localized pattern of radiation being projected using direct write lithography; developing the first intervening layer and reducing the height difference using a wet process, the developing step resulting in a wet-treated top surface of the substrate; measuring topographic metrics across the major surface of the substrate; comparing the topographical metric to a target topographical metric; responsive to determining that the topographical metric differs from a target topographical metric, spin-coating a second intervening layer onto the wet-treated upper surface of the substrate; exposing the substrate with a first localized pattern of radiation using direct write lithography; and developing the second intervening layer to further reduce the height difference; A method comprising:

4. moreover, responsive to determining that the topographical metrics match the target topographical metrics, forming a subsequent pattern of device features using conventional lithographic processes; 4. The method of claim 3, comprising:

5. 4. The method of claim 3, wherein the first intervening layer comprises a positive photoresist, and the first localized pattern of radiation is formed across the first surface.

6. 4. The method of claim 3, wherein the first intervening layer comprises a negative photoresist, and the first localized pattern of radiation is formed across the second surface.

7. The method of claim 5 , wherein the first localized pattern of radiation comprises actinic radiation.

8. The method of claim 3 , wherein the first localized pattern of radiation has a wavelength between 193 nm and 405 nm.

9. The method of claim 3 , further comprising measuring updated topographic metrics across the major surface of the substrate after forming the subsequent pattern of device features.

10. moreover, comparing the updated topographical metric to another target topographical metric; forming another subsequent pattern of device features in response to determining that the updated topographical metrics match the another target topographical metrics; 10. The method of claim 9, comprising:

11. moreover, comparing the updated topographical metric to another target topographical metric; in response to determining that the updated topographical metrics differ from the other target topographical metrics, spin-coating another intervening layer onto the substrate, exposing the substrate to the first localized pattern of radiation, and developing the other intervening layer; 10. The method of claim 9, comprising:

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