Patterned substrate

Abstract

A method for patterning a substrate in which a patterned photoresist structure can be formed on a substrate, the patterned photoresist structure having sidewalls. A conformal layer of spacer material can be deposited on the sidewalls. The patterned photoresist structure can then be removed from the substrate leaving behind the spacer material. The sidewall spacers can then be used as an etch mask to directionally etch the substrate to form a substrate having a target critical dimension.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 905,604, filed September 25, 2019, the contents of which are incorporated herein by reference. Technical Field

[0003] The implementation methods described herein generally involve patterned substrates. Background Technology

[0004] In the fabrication of semiconductor devices (especially at the microscale), various fabrication processes are performed, such as film deposition, etch mask creation, patterning, material etching and removal, and doping. These processes are repeated to form desired semiconductor device elements on a substrate. One specific technique is to use sidewall spacers or simply spacers. Spacers are typically formed by conformally depositing spacer material on a mandrel. The mandrel can be a topographic feature, such as a line, mesa, or hole. Any of a variety of conformal deposition processes can be used, such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). The result is a film covering all surfaces (horizontal and vertical) with approximately uniform thickness on both horizontal and vertical surfaces. Next, spacer opening etching is performed. Spacer opening etching is a directional (anisotropic) etching that removes an amount of spacer material at least equal to the deposited thickness. The result is the removal of spacer material from the horizontal surfaces, leaving spacers on the vertical surfaces (sidewalls of various features). The spacers can then be used as masks or structures for subsequent microfabrication. Therefore, it is important that the spacers have the desired structure for forming features with the desired critical dimensions in the substrate. Summary of the Invention

[0005] In one embodiment, this disclosure provides a method for patterning a substrate, the method comprising: forming a patterned photoresist structure on the substrate, the patterned photoresist structure having sidewalls having a predetermined sidewall slope corresponding to a target critical dimension (CD) of a substrate feature to be formed in the substrate; depositing a conformal layer of spacer material on the sidewalls; removing the patterned photoresist structure from the substrate such that the spacer material remains as sidewall spacers formed on the substrate; and directionally etching the substrate using the sidewall spacers as an etch mask to form a substrate feature having the target CD in the substrate.

[0006] In one embodiment, forming a patterned photoresist structure includes exposing a layer of photoresist to a pattern of photochemical radiation using a mask-based lithography system, the exposure being performed at a focal point corresponding to a predetermined sidewall slope.

[0007] In one embodiment, forming a patterned photoresist structure includes: forming a base layer of a predetermined material corresponding to a predetermined sidewall slope; forming a photoresist layer on the base layer; exposing the photoresist layer to a pattern of photochemical radiation using a mask-based photolithography system; wherein the base layer enhancement exposure layer step is used to form a potential patterned structure corresponding to the patterned photoresist structure having the predetermined sidewall slope; and removing a portion of the photoresist from the substrate such that the potential patterned structure remains on the substrate as a patterned photoresist structure.

[0008] In one embodiment, forming the substrate includes forming a material layer having a predetermined reflectivity, the material layer being configured to increase the intensity of photochemical radiation in the region of the photoresist adjacent to the substrate during exposure, such that the potential patterned structure has a predetermined sidewall slope.

[0009] In one embodiment, forming the substrate includes forming a material layer having active species, the material layer being configured to modify the latent pattern structure in a region of photoresist adjacent to the substrate, such that the latent pattern structure has a predetermined sidewall slope.

[0010] In one embodiment, the predetermined sidewall slope is configured to compensate for stress relaxation in the layer of spacer material after the patterned photoresist structure is removed.

[0011] In one embodiment, the layer of spacer material on the sidewall forms a first angle relative to the substrate surface, and the sidewall spacers form a second angle relative to the substrate surface, the second angle being closer to perpendicular than the first angle due to stress relaxation.

[0012] In one implementation, the target CD is equal to the thickness of the spacer material layer.

[0013] In one embodiment, forming a patterned photoresist includes forming another sidewall in different regions of the substrate, the other sidewall having another predetermined sidewall slope corresponding to another target critical dimension (CD), the sidewall slope and the other sidewall slope being configured to provide a uniform CD of substrate features in different regions of the substrate.

[0014] Another embodiment further includes: forming a substrate of a predetermined material corresponding to the formation of a predetermined sidewall slope; forming a layer of photoresist on the substrate, wherein the substrate enhancement exposure step is used to form a potential patterned structure corresponding to the patterned photoresist structure having a predetermined sidewall slope; and removing a portion of the photoresist from the substrate such that the potential patterned structure remains on the substrate as a patterned photoresist structure.

[0015] In one embodiment, the present disclosure provides a method of patterning a substrate, the method comprising: depositing an antireflective coating on a substrate, the antireflective coating comprising a solubility shift component; depositing a layer of photoresist on the antireflective coating; exposing the layer of photoresist to a pattern of actinic radiation using a mask-based lithography system, wherein a focus of the pattern of actinic radiation is set at a predetermined point that produces a latent pattern of structures having a sidewall taper, wherein an upper portion of the structures has a cross-section that is wider than a corresponding middle portion; diffusing the solubility shift component into a lower portion of the layer of photoresist; and developing the layer of photoresist, producing a photoresist structure having a sidewall taper, wherein a cross-sectional width of the photoresist structure decreases from a top of the photoresist structure to a bottom of the photoresist structure.

[0016] In one embodiment, the layer of photoresist comprises a first photoacid generator that generates a first photoacid in response to a first wavelength of light, and wherein the solubility shift component is a second photoacid that is a component of a second photoacid generator, the second photoacid generator generating a second photoacid in response to a second wavelength of light.

[0017] In one embodiment, the first wavelength of light is different than the second wavelength of light.

[0018] Another embodiment further comprises performing a flood exposure of a second wavelength of light on the substrate after exposing the layer of photoresist to the pattern of actinic radiation using the mask-based lithography system.

[0019] In one embodiment, the first wavelength of light is equal to the second wavelength of light.

[0020] In one embodiment, the exposing from the pattern of actinic radiation using the mask-based lithography system is sufficient to generate an amount of photoacid from the second photoacid generator.

[0021] In one embodiment, the solubility shift component is an acid deposited on the antireflective coating.

[0022] In one embodiment, the solubility shift component is a free acid within the antireflective coating.

[0023] Another embodiment further comprises forming sidewall spacers on the photoresist structure, the sidewall spacers taking on the sidewall taper of the photoresist structure; and removing the photoresist structure.

[0024] In one embodiment, the removing the photoresist structure is such that a top of the sidewall spacer from a given photoresist structure is reduced in geometric distance from one another upon removal of the given photoresist structure.

[0025] In one embodiment, the antireflective coating is partially reflective and sufficient to reflect a portion of the pattern of actinic radiation back into the layer of photoresist to create more photoacid at the bottom of the layer of photoresist.

[0026] In one embodiment, the concentration of the solubility shift component in the antireflective coating is selected so that the sum of the photoacid generated from the layer of photoresist and the photoacid generated from the antireflective coating is sufficient to result in photoresist structures having a sidewall taper.

[0027] In one embodiment, the present disclosure provides a method of patterning a substrate, the method comprising: depositing an antireflective coating on a substrate; depositing a layer of photoresist on the antireflective coating; exposing the layer of photoresist to a pattern of actinic radiation using a mask-based lithography system, wherein a focal point of the pattern of actinic radiation is set at a predetermined point that creates a latent pattern of structures having a sidewall taper, wherein an upper portion of the structures has a wider cross-section than a corresponding lower portion; and developing the layer of photoresist to create photoresist structures having a sidewall taper, wherein a cross-sectional width of the photoresist structures decreases from a top of the photoresist structures to a bottom of the photoresist structures.

[0028] In one embodiment, the present disclosure provides a method of patterning a substrate, the method comprising: identifying an effective spacer CD created by spacers formed on a substrate; depositing an antireflective coating on the substrate; depositing a layer of photoresist on the antireflective coating; exposing the layer of photoresist to a pattern of actinic radiation using a mask-based lithography system, wherein a focal point of the pattern of actinic radiation is set at a predetermined point that creates a latent pattern of structures having a predetermined sidewall taper; developing the layer of photoresist to create photoresist structures having the predetermined sidewall taper; forming sidewall spacers on the photoresist structures, the sidewall spacers assuming the predetermined sidewall taper; and removing the photoresist structures from the substrate, thereby creating sidewall spacers having a modified sidewall taper that creates the effective spacer CD when a pattern defined by the sidewall spacers is transferred into an underlying layer.

[0029] Note that this Summary section does not specify every embodiment and / or incremental improvement of the present disclosure or claimed application. Rather, this Summary is merely a preliminary discussion of different embodiments and corresponding points of novelty as compared to conventional technologies. For further details and / or possible points of view, the reader is directed to the particular embodiments section and corresponding drawings discussed further below. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flowchart of a method of patterning a substrate.

[0031] Figure 2 Three different resist profiles are shown, resist profile after spacer cladding generates constant spacer thickness, and effective critical dimension in each of the resist profiles after spacer etch mandrel pull (SEMP) etch relative to the actual critical dimension.

[0032] Figure 3 Three different resist profiles are shown, where the resist for“-defocus” has a wider bottom that narrows toward the top, the resist for“focus” has a top and bottom of approximately equal width, and the resist for“+defocus” has a wider top that narrows toward the bottom.

[0033] Figure 4 Cross-sectional transmission electron microscope (TEM) images showing adjustment of resist profile by changing focus are shown, where dose = 34 mJ / cm 2 .

[0034] Figure 5 An example of controlling profile via active species loaded into the underlayer is shown, where the underlayer contains an active species (e.g., a photoacid generator, PAG) to generate an acid, where the acid then diffuses into the photoresist, which increases the acid concentration in the photoresist bottom.

[0035] Figure 6 Resist profile as a function of active species concentration loaded into the underlayer is shown, where, for example, as the amount of acid in the underlayer increases, the concentration gradient in the resist becomes steeper. DETAILED DESCRIPTION

[0036] As described in the background, it is important that the spacer have the intended structure for forming features in the substrate with the desired critical dimension (CD). The spacer can be formed on a mandrel of any material. Typically, the first material that forms the topographical relief pattern is photoresist. Thus, it is desirable to form a spacer on a photoresist pattern. An important challenge with using photoresist as the mandrel is that photoresist is a relatively soft material and is often developed into a profile that does not have a vertical profile. The sidewalls can be tilted inwards or outwards, depending on how the lithographic exposure is performed. Furthermore, when a spacer is deposited on some photoresist or other soft mandrel, the compressive or tensile stress in the deposited film can change the profile of the soft mandrel. For example, the spacer can be tilted or not perfectly perpendicular to the substrate surface. The spacer is often used as an etch mask for pattern transfer using directional etching. A tilted spacer can then make the effective critical dimension much larger than the thickness of the spacer.

[0037] Another challenge with using photoresist mandrels is that while the photoresist is on the substrate, the sidewall spacers can have an initial angle, but when the photoresist is removed (stripped off), the removal process typically produces sidewall spacers with a changed angle relative to the substrate. Therefore, even if the initial sidewall spacers are perfectly perpendicular to the substrate, the mandrel removal process can produce sidewall spacers with different angles, such as tilting more towards each other.

[0038] Figure 1 This is a flowchart of a method 100 for traversing one embodiment of a patterned substrate.

[0039] The first step, S101, involves forming a patterned photoresist structure on a substrate. This patterned photoresist structure has sidewalls with a predetermined sidewall slope corresponding to a target critical dimension of the substrate feature to be formed in the substrate. Then, S102, a conformal layer of spacer material is deposited on the sidewalls. Next, S103, the patterned photoresist structure is removed from the substrate, leaving the spacer material as sidewall spacers formed on the substrate. Finally, S104, the substrate is oriented to etch using the sidewall spacers as an etch mask to form a substrate feature with a target CD in the substrate. The patterned photoresist structure on the substrate can be formed using one or more of the disclosed techniques, including using inverse focusing, an underlayer for modulating reflectivity, and / or an underlayer carrying active species to produce a predetermined sidewall cone or slope.

[0040] The disclosed technology provides effective spacer CD control for spacers formed on a soft mandrel. In other words, the disclosed technology can use various methods to adjust or correct different profiles entering the photoresist (i.e., the resist). Figure 2 A conceptual illustration of the resist profile and the resulting effective spacer CD is shown. Figure 2 The top / first row (labeled "3 different resist profiles") shows cross-sectional views of three different resist profiles on the substrate, where the left photoresist core (labeled "-defocus") has a wider base and tapers towards the top, the middle photoresist core (labeled "focus") has a base and top of approximately the same width, and the right photoresist core (labeled "+defocus") has a wider top and tapers towards the base. The term "effective spacer CD" as used herein refers to the projected CD during RIE (Reactive Ion Etching) transfer. In other words, viewed from the z-direction, a tilted spacer will produce a shadow greater than its thickness, and this shadowed area can be considered the effective CD. The term "actual CD" as used herein refers to the thickness of the spacer. When the spacer has a vertical or near-vertical orientation, the actual CD is transferred during RIE transfer. Figure 2Example illustrations of valid CDs and actual CDs are shown at the bottom / third line (labeled "Valid CDs vs. Actual CDs").

[0041] Because RIE etching is directional (anisotropic) etching, the transferred pattern is a shadow of the mask. Therefore, tilted spacers can mask beyond the thickness of a given spacer. Then, due to the shadow created by the tilt, the transferred CD may appear larger than the actual CD. This is in… Figure 2 As shown in the bottom row. Note that the amount of shading or effective CD depends on the tilt angle. Figure 2 The first line shows how the incoming resist profile can have different degrees of sidewall angles. Figure 2 In the second / middle row (labeled "Constant Spacer Thickness"), the deposited spacers from the spacer coating can follow the contour of the incoming photoresist core. Some spacer materials can also further compress a given photoresist material.

[0042] Spacer deposition is the most uniform process, where the deposition amount cannot be controlled based on the location on a single wafer to adjust the spacer CD. In other words, the deposition on the wafer is uniform. However, the disclosed technique controls the effective spacer CD at specific locations on the wafer for inter-wafer control by providing an additional knob to adjust the process. The spacer can then be deposited directly onto a photoresist having a modified profile depending on the desired effective CD. It should be noted that while the sidewall spacers may have a first angle when the photoresist is on the substrate, the removal process (stripping) typically produces sidewall spacers with a changed angle relative to the substrate. Therefore, even if the initial sidewall spacers are perfectly perpendicular to the substrate, the mandrel removal process can produce sidewall spacers with different angles, for example, tilted more towards each other. This can be achieved through... Figure 2 As seen in [the text]. Figure 2 As shown on the left ("-Defocus" column), when the photoresist mandrel has a substrate wider than the top, there are angled sidewall spacers, and the angle of inclination increases after removal. Figure 2 As shown in the middle column (“Focus” column), even with perfectly vertical spacers, removing the photoresist mandrel can cause the spacers to tilt. Therefore, the technique described herein involves forming a photoresist mandrel with an inverted slope or inverted cone shape; for example, a mandrel with a wider top that narrows towards the substrate. The initially formed sidewall spacers will then not be perpendicular to the substrate, but rather, after removing the photoresist mandrel, spacers that are normal to or perpendicular to the substrate are removed, as can be achieved by... Figure 2seen in the right column of FIG. 1 1 (“+defocus” column). Thus, in one embodiment, a straight sidewall spacer is presented with an inverse taper (i.e., inverse slope) profile. That is, the layer of spacer material on the sidewall can be formed at a first predetermined angle that is away from perpendicular with respect to the surface of the substrate, but is designed to compensate for stress relaxation upon removal of the photoresist. Then, after removal of the photoresist, the sidewall spacer can form a second angle that is closer to perpendicular (than the first angle) due to stress relaxation.

[0043] One embodiment includes a reverse focus technique. This includes adjusting the focus to adjust the photoresist profile and sidewall angle (SWA) that affect the effective spacer CD. The focus shift can be performed on the scanner or a stand-alone platform. Figure 3 The results of the focused photoresist 204, the reduced focus photoresist 202, and the increased focus photoresist 206 are shown. The focus of the exposed pattern is essentially raised above the point of the layer of photoresist that would normally be used. This is a change in focus in the z-direction. While this positive defocus causes the sidewalls to be exposed at an angle, the change in the center point of the focus - for some photoresists - can mean that less exposure can cause a deprotection reaction at the bottom of the layer of photoresist. Figure 4 is a cross-sectional magnified image of a photoresist adjusted by adjusting the focus (f) of the exposure. In this particular example, the dose is 34 mJ / cm 2 Note that in Figure 4 In the image on the right (f = -40 nm), the upper portion of the lines (mandrels) have an inverse taper, but each line has a foot. Thus, the techniques herein can also increase the exposure to help remove the foot.

[0044] The techniques herein include using a secondary acid (or base) delivery to increase the initial exposure to remove the foot. There are several alternative embodiments.

[0045] In one implementation, active species are loaded into an underlayer (e.g., an anti-reflective coating (ARC) layer). One example of an active species is an acid. The acid within the underlayer diffuses from the underlayer into the resist, thereby increasing the acid concentration at the bottom of the exposed region. Rather than reflecting additional light (which does not experience the standing wave), the additional light is absorbed and produces additional acid, which diffuses to the bottom of the resist, helping to mitigate footing and to adjust the sidewall angle. Thus, the underlayer can increase or enhance the exposure step to provide a greater acid concentration than would be provided without the underlayer, which provides a correspondingly greater resist removal upon development of the resist after exposure. As another example, the underlayer can include a base that increases or enhances the exposure step to provide a greater base concentration than would be provided without the underlayer, which provides a correspondingly less resist removal upon development of the resist after exposure. In addition, the underlayer can be made somewhat more reflective, which can increase the intensity of the radiation near the interface with the underlayer to release a greater concentration of acid from the photoresist itself. Figure 5 is a diagram showing a substrate segment illustrating the progression of mask-based photolithography exposure with an underlayer load. Figure 5 includes a resist 406 (i.e., a photoresist), an underlayer 404, and a substrate 402. In this example, the underlayer 404 (i.e., the layer underneath) contains a photoacid generator (PAG) to generate acid (e.g., H+). Alternatively, a base can be used. The PAG is reactive to actinic radiation 408 from the mask-based exposure. After the acid is generated, a bake step is utilized to diffuse the acid into the resist 406. This increases the acid concentration at the bottom of the resist 406. Note that the layer of photoresist 406 includes a photoactive species (e.g., PAG), but the activation at the lower portion of the layer of photoresist 406 can be less than the activation at the upper portion of the layer of photoresist 406. Thus, having a second acid supply that can be brought into the layer of photoresist 406 from the underlayer can help with uniform protection / deprotection (solubility change), enabling increased resolution or sidewall angle during development.

[0046] Figure 6 shows how using active species loaded into the underlayer 404 can also be used as a footing mitigation. The profile is a function of the concentration of active species loaded into the underlayer 404. For this example, as the amount of acid in the underlayer 404 increases, the concentration gradient in the resist becomes steeper, as shown by the different shapes of the photoresist 406.

[0047] In embodiments with two different PAGs, one in the photoresist and the other in the ARC layer, they can respond to the same wavelength of light or different wavelengths of light (out-of-band illumination). For example, after an initial patterning exposure using a 193 nm wavelength scanner, an I-line flood exposure can be performed to activate the amount of PAG in the ARC. Note that for the flood exposure, photoacid will be generated uniformly, but the amount generated by itself is not enough to dissolve the layer of photoresist, but when combined with the other acid, the total amount is enough to dissolve. For example, the trench can receive an amount of acid, and the underlying layer can provide the rest of the acid to remove the footing and create an inverse tapered profile. In another embodiment, more than two PAGs can be used to achieve the desired result.

[0048] In another embodiment, the bottom layer reflectivity is modulated. The amount of reflectivity of a given bottom layer is adjusted by changing the material composition. By reflecting more light from the bottom layer, the acid concentration near the bottom layer is increased and affects the resist profile. In other embodiments, the thickness of the anti-reflective coating can be adjusted for the desired acid concentration and / or reflectivity.

[0049] Thus, in one example embodiment, sidewall angle adjustment can adjust the effective CD by sub-nanometer to nanometer corrections.

[0050] In the preceding description, specific details have been set forth, such as a particular geometry of a processing system, and descriptions of various components and processes used as examples of various means. It should be understood, however, that techniques herein can be practiced in other embodiments that depart from these specific details, and that such embodiments are within the scope of the techniques. The implementations 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 in order to provide a thorough understanding. Nevertheless, embodiments can be practiced without such specific details. Components having substantially the same functional configurations are denoted by the same reference characters, and thus any redundant description can be omitted.

[0051] Various techniques have been described as multiple discrete operations in order to assist in understanding various embodiments. The order of describing these operations should not be construed as a requirement or a limitation for these operations to be performed in the order described. Indeed, these operations need not be performed in the order described. The operations described can be performed in a different order than described. Various additional operations can be performed and / or described operations can be omitted in additional embodiments.

[0052] A "substrate" or "target substrate" as used herein generally refers to the object being processed in accordance with the present application. The substrate can include any material portion or structure of a device, particularly a semiconductor or other electronic device, and can be, for example, a base substrate structure (e.g., a semiconductor wafer, reticle) or a layer (e.g., a thin film) on or covering the base substrate structure. Thus, the substrate is not limited to any particular base structure, underlayer or cover layer, patterned or unpatterned, but is intended to encompass any such layer or base structure, as well as any combination of layers and / or base structures. The description can refer to a particular type of substrate, but this is merely for illustrative purposes.

[0053] Those skilled in the art will further appreciate that the operations of the techniques described above can be varied significantly while still being encompassed by the scope of the present disclosure. Accordingly, the foregoing description of embodiments of the application is not intended to be limiting. Rather, any limitations with respect to embodiments of the application presented in the following claims are intended to cover all applications of such limitations.

Claims

1. A method for patterning a substrate, the method comprising: A patterned photoresist structure is formed on the substrate, the patterned photoresist structure having sidewalls having a predetermined sidewall slope corresponding to a target critical dimension of a substrate feature to be formed in the substrate; A conformal layer of spacer material is deposited on the sidewall, such that the spacer material on the sidewall has a first projected critical size that is different from the target critical size; The patterned photoresist structure is removed from the substrate such that the spacer material remains as a sidewall spacer formed on the substrate and the sidewall spacer has a second projection critical dimension due to the relaxation of stress in the spacer material; as well as The substrate is etched directionally using the sidewall spacers as an etching mask to form a substrate feature having a second projection critical size, wherein the second projection critical size is closer to the target critical size than the first projection critical size. The patterned photoresist structure has an inverted conical profile, and The deposited spacer material forms a layer of uniform thickness on the sidewall, and the deposited spacer material follows the contour of the patterned photoresist structure.

2. The method according to claim 1, wherein, Forming a patterned photoresist structure involves using a mask-based lithography system to expose a layer of photoresist to a pattern of photochemical radiation, performing exposure at a focal point corresponding to the predetermined sidewall slope.

3. The method according to claim 1, wherein, The formation of patterned photoresist structures includes: Corresponding to the predetermined sidewall slope, a bottom layer of predetermined material is formed. A layer of photoresist is formed on the underlying layer. A mask-based lithography system is used to expose the photoresist layer to a pattern of photochemical radiation, wherein the bottom layer enhancement exposure step forms a potential patterned structure corresponding to the patterned photoresist structure having the predetermined sidewall slope, and A portion of the photoresist is removed from the substrate, such that the potential patterned structure remains on the substrate as the patterned photoresist structure.

4. The method according to claim 3, wherein, Forming the substrate includes forming a material layer with a predetermined reflectivity configured to increase the intensity of photochemical radiation in the region of the photoresist adjacent to the substrate during exposure, such that the underlying pattern structure has the predetermined sidewall slope.

5. The method according to claim 3, wherein, Forming the substrate includes forming a material layer with active species configured to modify the latent pattern structure in a region of photoresist adjacent to the substrate, such that the latent pattern structure has the predetermined sidewall slope.

6. The method according to claim 1, wherein, The predetermined sidewall slope is configured to compensate for stress relaxation in the spacer material layer after the patterned photoresist structure is removed.

7. The method according to claim 6, wherein, The layer of spacer material on the sidewall forms a first angle relative to the substrate surface, and the sidewall spacer forms a second angle relative to the substrate surface, the second angle being closer to perpendicular than the first angle due to stress relaxation.

8. The method according to claim 7, wherein, The target critical dimension is equivalent to the thickness of the spacer material layer.

9. The method according to claim 1, wherein, Forming a patterned photoresist includes forming another sidewall in different regions of the substrate, the other sidewall having another predetermined sidewall slope corresponding to another target critical size, the sidewall slope and the other sidewall slope being configured to provide a uniform critical size for substrate features in different regions of the substrate.

10. The method according to claim 2, further comprising: Corresponding to the predetermined sidewall slope, a bottom layer of predetermined material is formed. A layer of photoresist is formed on the underlying layer, wherein the underlying layer enhancement exposure step is used to form a potential patterned structure corresponding to the patterned photoresist structure having the predetermined sidewall slope, and A portion of the photoresist is removed from the substrate, such that the potential patterned structure remains on the substrate as the patterned photoresist structure.

11. A method for patterning a substrate, the method comprising: An anti-reflective coating is deposited on a substrate, the anti-reflective coating comprising a solubility transfer component; A layer of photoresist is deposited on the anti-reflective coating; A mask-based lithography system is used to expose the photoresist layer to a photochemical radiation pattern, wherein the focal point of the photochemical radiation pattern is set at a predetermined point, which produces a potential pattern with a structure having inverted conical sidewalls, wherein the upper part of the structure has a wider cross-section compared to the cross-section of the corresponding middle part. The solubility transfer component is diffused into the lower part of the photoresist layer; and Developing the photoresist layer results in a photoresist structure having inverted conical sidewalls, wherein the cross-sectional width of the photoresist structure decreases from the top to the bottom of the photoresist structure. The method further includes: Sidewall spacers are formed on the photoresist structure, the sidewall spacers having an inverted conical shape and a first projected critical dimension; and The photoresist structure is removed, causing the sidewall spacers to have a second projected critical size that differs from the target critical size of the substrate feature to be formed due to stress relaxation. The second projected critical size is closer to the target critical size than the first projected critical size. The sidewall spacers form a layer with a uniform thickness and follow the contour of the photoresist structure.

12. The method according to claim 11, wherein, The photoresist layer comprises a first photoacid generator that generates a first photoacid in response to light of a first wavelength, and wherein the solubility transfer component is a second photoacid that is a component of a second photoacid generator that generates a second photoacid in response to light of a second wavelength.

13. The method according to claim 12, wherein, The first wavelength of the light is different from the second wavelength of the light.

14. The method of claim 13, further comprising, after exposing the photoresist layer to the pattern of photochemical radiation using the mask-based lithography system, performing whole-sheet exposure of the substrate with light of the second wavelength.

15. The method according to claim 11, wherein, The solubility transfer component is an acid deposited on the antireflective coating.

16. The method according to claim 11, wherein, The solubility transfer component is the free acid within the antireflective coating.

17. The method according to claim 11, wherein, Removing the photoresist structure results in a decrease in the geometric distance between the tops of the sidewall spacers from the given photoresist structure when the given photoresist structure is removed.

18. The method according to claim 11, wherein, The antireflective coating is partially reflective and sufficient to reflect a portion of the photochemical radiation pattern back into the photoresist layer to generate more photoacid at the bottom of the photoresist layer.

19. The method according to claim 11, wherein, The concentration of the solubility transfer component in the antireflective coating is selected such that the sum of the photoacids generated from the photoresist layer and the photoacids generated from the antireflective coating is sufficient to result in the photoresist structure having the inverted conical sidewall shape.

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