Wafer warpage correction method using direct-written stress film

Abstract

Techniques herein include methods for forming direct-write tunable stress films and using said stress films to correct wafer bow. The method may be performed in a coater / developer tool or a track-based tool. The stressed film may be based on, but is not limited to, a film that undergoes cross-linking / de-cross-linking under an external stimulus where direct writing is achieved by 365 nm exposure and subsequent curing is used to "build in" the stress. A development step may be eliminated, providing the additional significant advantage that the film remains flat. The amount of warping (or internal stresses that create or affect the warping properties) may be tuned by exposure dose, bake temperature, bake time, and bake times.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to semiconductor manufacturing methods, and more particularly, to wafer bow mitigation.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 175,123, filed April 15, 2021, and U.S. Patent Application No. 17 / 703,072, filed March 24, 2022, which are incorporated by reference in their entireties herein. [Background technology]

[0003] The background description provided herein is intended to generally present the context of the present disclosure. The inventors' work to the extent described in this background section, and aspects of the description that would not otherwise qualify as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art to the present disclosure.

[0004] Semiconductor manufacturing involves a number of different steps and processes. One typical manufacturing process is known as photolithography (also called microlithography). Photolithography uses radiation, such as ultraviolet or visible light, to create fine patterns in semiconductor device designs. Semiconductor manufacturing techniques, including photolithography, etching, film deposition, surface cleaning, metallization, and the like, can be used to construct a variety of semiconductor devices, such as diodes, transistors, and integrated circuits.

[0005] Photolithography techniques are performed using exposure systems (also called exposure tools). Exposure systems typically include an illumination system, a reticle (also called photomask) or spatial light modulator (SLM) that creates the circuit pattern, a projection system, and a wafer alignment stage that aligns a semiconductor wafer covered with a photosensitive resist. The illumination system illuminates an area of ​​the reticle or SLM with a (preferably) rectangular slot illumination field. The projection system projects an image of the illuminated area of ​​the reticle pattern onto the wafer. For the projection to be accurate, it is important that the wafer is exposed to the light pattern on a relatively flat or planar wafer, preferably with a height deviation of less than 10 microns. Therefore, a method is needed to correct any wafer bow. Summary of the Invention [Means for solving the problem]

[0006] The present disclosure relates to a method of processing a substrate, comprising the steps of forming a bow-tuning stress film on a backside of a wafer, the wafer including a processing side and a backside opposite the processing side, the bow-tuning stress film including a stress-modification agent, the bow-tuning stress film being sensitive to a predetermined wavelength of actinic radiation; exposing the bow-tuning stress film to a pattern of actinic radiation at the predetermined wavelength, the bow-tuning stress film configured to release the stress-modification agent at locations along the bow-tuning stress film exposed to the pattern of actinic radiation, a concentration of the released stress-modification agent corresponding to the pattern of actinic radiation; and performing a curing process, the curing process activating the released stress-modification agent and causing stress changes in the bow-tuning stress film, the stress changes modulating the bow of the wafer.

[0007] The present disclosure additionally provides a method for forming a first warp tuned stress film on a backside of a wafer, the wafer including a processing side and a backside opposite the processing side, the first warp tuned stress film configured to release a first stress tuned agent in response to actinic radiation having a first predetermined wavelength; forming a second warp tuned stress film on the first warp tuned stress film, the second warp tuned stress film configured to release a second stress tuned agent in response to actinic radiation having a second predetermined wavelength; and exposing the first warp tuned stress film and the second warp tuned stress film to a first pattern of actinic radiation at the first predetermined wavelength, the first warp tuned stress film configured to release the first stress tuned agent at locations along the first warp tuned stress film exposed to the first pattern of actinic radiation, the released first stress tuned agent being a first stress tuned agent. a first predetermined wavelength of actinic radiation, the second warp tuned stress film being configured to release a second stress modulating agent at locations along the second warp tuned stress film exposed to the second pattern of actinic radiation, the concentration of the released second stress modulating agent corresponding to the second pattern of actinic radiation; and performing a curing step, the curing step activating the released first stress modulating agent and the released second stress modulating agent, the curing step creating a first stress change in the first warp tuned stress film and a second stress change in the second warp tuned stress film, the first stress change and the second stress change together modulating the bow of the wafer.

[0008] It should be noted that this Summary section does not specify all embodiments and / or inherently novel aspects of the invention described in this disclosure or the claims. Instead, the Summary of the Invention only provides a preliminary discussion of different embodiments and corresponding points of novelty. For further details and / or anticipated aspects of the invention and embodiments, the reader is directed to the Detailed Description of the Invention section of this disclosure and corresponding figures, which are discussed further below.

[0009] Various embodiments of the present disclosure, proposed by way of example, will now be described in detail with reference to the following figures, in which like numbers refer to like elements, and in which: [Brief description of the drawings]

[0010] [Figure 1A] 1 is a schematic perspective view of layers on a wafer having a defect introduced into one of the layers; [Figure 1B] 1 is a schematic diagram of various types and degrees of resulting wafer bow. [Figure 2A] 1 is a stress map for a warp relaxed stress film disposed on a wafer and exposed to actinic radiation according to an embodiment of the present disclosure. [Figure 2B] 1 is a stress map for a warp relaxed stress film disposed on a wafer and exposed to actinic radiation according to an embodiment of the present disclosure. [Figure 2C] 1 is a stress map for a warp relaxed stress film disposed on a wafer and exposed to actinic radiation according to an embodiment of the present disclosure. [Diagram 3] 1 is a cross-sectional substrate segment showing structures or devices formed on the surface according to an embodiment of the present disclosure. [Figure 4] 1 is a cross-sectional substrate segment showing a bow-tuning stress film formed on the backside of a wafer according to an embodiment of the present disclosure. [Diagram 5] 1 is a cross-sectional substrate segment showing exposure of a stress film according to an embodiment of the present disclosure. [Figure 6]1 is a cross-sectional substrate segment showing a stressed film after exposure according to an embodiment of the present disclosure. [Figure 7] 1 is a flowchart of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following disclosure shows various embodiments or examples for implementing various features of the presented subject matter. To simplify the disclosure, specific examples of components and configurations are described below. It should be understood that these are merely examples and are not intended to be limiting. For example, the formation of a first feature above or on a second feature in the following description may include an embodiment in which the first feature and the second feature are formed in direct contact with each other, or may include an embodiment in which an additional feature may be formed between the first feature and the second feature such that the first feature and the second feature may not be in direct contact with each other. In addition, the disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purposes of brevity and clarity and does not in itself refer to the relationship between the various embodiments and / or configurations discussed. Furthermore, spatially relative terms such as "top", "bottom", "lower", "below", "lower", "lower", "upper", "above" and the like may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures for ease of description. Spatial relationship terms are intended to include different orientations of the device during use or operation in addition to the orientation depicted: the device may be in other orientations (rotated 90 degrees or at other orientations) and the spatial relationship descriptors used herein may be interpreted accordingly.

[0012] The order of description of the different steps described herein is shown for the sake of clarity. In general, these steps can be performed in any suitable order. Also, although different features, techniques, configurations, etc. herein may be referred to in different places in this disclosure, it is understood that each concept can be performed independently of each other or in combination with each other. Thus, the present invention can be embodied and viewed in many different ways.

[0013] Described herein are techniques for providing spin-on direct-write adjustable stress films and methods for correcting wafer bow. The processes herein can be performed in a coater-developer tool (also known as a track tool). Such techniques achieve corrected wafer bow with fewer and less expensive steps. The spin-on films can be based on, but are not limited to, films that undergo cross-linking / de-cross-linking under an external stimulus where direct-write is achieved by 365 nm exposure and subsequent curing is used to "pattern-in" the stress. Furthermore, the films need not be limited to spin-on processes and other deposition methods may be used. A develop step is not required by the techniques herein (although it may be optional), but it also provides significant benefits. The amount of bow (or internal stresses that create or affect the bow characteristics) can be adjusted with exposure dose, bake temperature, bake time, and bake times. However, the stress tuning films herein may be organic in nature and may have properties or components that crosslink when exposed to light or crosslink after exposure to light followed by a bake or cure step. The nature of the film also allows for backside wafer coating.

[0014] In the fabrication of 3D NAND memory devices, device structures may extend vertically from the wafer's processing surface. As more memory is stored in these devices, they become heavier. FIG. 1A is a schematic perspective view of layers on a wafer where defects are introduced in one of the layers. For example, 128 layers may be used for a 3D NAND device on a 300 mm wafer. As shown, defects in an underlying previous layer may be amplified to cause severe bowing in a later layer. FIG. 1B shows that systematically increasing the number of layers in the front side 3D NAND stack further increases the bowing of the wafer, increasing the severity of the problem. This can cause problems including non-uniformity, non-planarity, overlay mismatch in lithography or other processes, and poor wafer handling.

[0015] Some mitigation strategies include depositing a silicon nitride film on the backside of the wafer, for example by chemical vapor deposition (CVD), which can create a large amount of stress on the wafer and the devices. A certain portion of the silicon nitride is then imaged, illuminated, or exposed, and then removed to relieve the stress at a particular point on the wafer, which can reshape the wafer differently. A problem posed by the silicon nitride film method is that it requires the provision of different tools, which can mean that a simple track-based process may be incompatible. Thus, it may be necessary to load the wafer into an entirely different tool. Furthermore, this method can also take time to apply the desired amount of silicon nitride to the backside of the wafer. In addition, this method is generally a very complicated process of imaging the silicon nitride film and adjusting the pattern in the silicon nitride film to mitigate the bow of the wafer.

[0016] As described herein, an organic-based crosslinkable bow mitigating film may be deposited on the backside of the wafer. The bow mitigating film may be flexible for local bow mitigation as well as global bow mitigation. In one embodiment, global bow mitigation may be applied to the film. In one embodiment, local bow mitigation may be applied via a programmable direct-write stress pattern on the film on the backside of the wafer. The direct-write stress pattern may be based on a frontside bow tuning stress map (referred to herein as a "stress map"). Notably, the bow mitigating film is a polymer-based organic film that is deposited on the backside of the wafer using a tool that may enable continuous processing in a track-based process. Given a predetermined wavelength of actinic radiation, the film may be imaged, illuminated, or exposed based on the stress map to build stress into the film and thus the wafer that mitigates undesired bow on the opposite side or surface. Furthermore, the exposure process, which may include an exposure step and a heating or baking step, does not require a develop step. Thus, this method may be considered as a direct-write process for producing bow mitigating films. The bow mitigating film may also be described as a stressed film in that the film may incorporate stress to mitigate the bow of the wafer.

[0017] Related to the impact of warpage on manufacturing tools, the tools may handle (i.e., move, transport, and manipulate) the wafers, but may experience handling issues as the wafer warpage approaches and exceeds 300 μm. Notably, the methods described herein may allow for an increase in secondary warpage relief of up to 150 μm while maintaining a primary warpage relief of 300-400 μm. Although this is direct write, it may still include a development step. The development step may allow areas not exposed to light to have flexibility at higher cure temperatures if there is unexposed material present. For example, these areas may also be crosslinked at higher temperatures if the decomposition temperature of the photoacid generator is not high.

[0018] In terms of chemistries, the methods described herein may utilize chemistries including epoxy acrylates, epoxy novolacs, benzenecyclobutadiene (BCB) chemistries where the Diels-Alder reaction can induce crosslinking, and polyimides. Other types of chemistries that may be used include photoinitiated chemistries where irradiation and subsequent heating, or exposure alone, results in crosslinking or bond rearrangements to form some type of stress. If the wafer bow can be mitigated using a backside coat on the track, the complicated silicon nitride film deposition step can be eliminated.

[0019] In one embodiment, an organic formulation may be deposited on the surface of the wafer through a spin-coating process or any deposition process. The film may be baked to remove excess solvent. The film may then be exposed to a pattern of actinic radiation. This pattern of actinic radiation may define or be based on the stress tuning pattern. Various lithography tools may be used. Preferably, a direct-write laser or lithography tool may be used. This may be a digital light processing (DLP) chip, a laser galvanometer, etc., that projects the pattern as an image or as a scan. In one embodiment, a mask-based lithography exposure using a scanner or stepper tool may be used. Although direct-write tools have a lower resolution than mask-based tools, the resolution required to fine-tune the stress may be much lower compared to patterning a transistor. Also, a stress map created with a mask is static, whereas using a direct-write tool may be dynamic, so the stress map may be created or projected and changed for each wafer as needed.

[0020] As described herein, the wavelength of the light (i.e., actinic radiation) may be 365 nm, but other wavelengths may be used as well. The wavelength may depend on the components contained in a given organic film. The embodiments herein may also include using multiple films that respond to different wavelengths of light. After exposure, the film may be heated in a post-exposure bake. However, a development step is not required, and the film may then be cured at a higher temperature, the time and temperature of which may depend on the film thickness and the amount of stress required. Note that a development step may be performed before curing, but this is optional. The curing temperature should be high enough to induce more complete cross-linking in the film. With the initial flood exposure and curing of the organic stress film, a wafer bow of tens or hundreds of microns may be achieved.

[0021] Referring now to the drawings, FIGS. 2A-2C are stress maps of a warpage-modified stress film disposed on a wafer and exposed to actinic radiation, according to an embodiment of the present disclosure. In one embodiment, the wafer may include a first surface and a second surface. For example, the first surface of the wafer may be a processing surface on which target devices are fabricated. The second surface may be a backside of the wafer. The backside of the wafer may have a warpage-modulated stress film (referred to herein as a "stress film") formed thereon. The stress film may be an organic film or a polymer-based film.

[0022] In one embodiment, Figures 2A-2C show how an organic stress film can affect the bow of a wafer. The stress film can be deposited on the backside of the wafer, for example, by spin coating. Other deposition processes can be contemplated, such as sputter coating, spray coating, doctor blading, CVD, physical vapor deposition (PVD), and atomic layer deposition (ALD), among others. The stress film can be exposed according to a predefined pattern or shape, such as a strip of stress film through the center of the wafer. As shown in Figures 2A-2C, a 100 mm strip of stress film was exposed under the center of the wafer and exposed to light having a wavelength of 365 nm. The wafer containing the exposed stress film can be cured at a higher temperature after being heated in a post-exposure bake. The additional curing step increases the bow of the wafer, allowing for a tunable stress film. Each of the stress maps is accompanied by the same table with additional process information for reference.

[0023] 2A-C show the processing conditions in the table (left) and the corresponding stress map of the epoxy novolac film along with the resulting saddle pattern image through the center of the wafer.

[0024] In FIG. 2A, the first cure was performed at 175° C. for 10 minutes, resulting in a wafer bow of about 88 μm for a stressed film having a thickness of 17 μm.

[0025] In FIG. 2B, a second cure was performed at 200° C. for an additional 10 minutes, resulting in a wafer bow of about 214 μm.

[0026] In FIG. 2C, a third cure was performed at 200° C. for an additional 5 minutes, resulting in a wafer bow of about 260 μm.

[0027] As mentioned above, chemistries included in such stress films include, but are not limited to, epoxy acrylates, epoxy novolacs, BCB chemistries where Diels-Alder reactions can induce crosslinking, and polyimides. Again, the wafer bow shown in Figures 2A-C shows that stress films can indeed cause wafer bowing and therefore can be used on wafers that already have bowing due to devices fabricated thereon to mitigate or correct said wafer bowing.

[0028] As mentioned above, coater / developer systems may be used herein for spin-on deposition of stressed films. These tools may include multiple modules for coating the wafer, baking the wafer, and developing the film. The coater / developer tools described herein may also include a direct write exposure module. The coater / developer system may then shuttle the wafer between various spin coating, baking / curing, and exposure modules, or to an attached scanner / stepper tool. Additionally, the coater / developer tools described herein may also include point-of-dispense mixing. That is, chemicals may be mixed at or near the dispense nozzle just prior to dispensing to the wafer. For example, solvents may be added to the resist at the nozzle to adjust viscosity or film thickness.

[0029] The techniques herein may be used to mitigate or counteract bowing due to microfabrication processes. The stressed films herein may be deposited multiple times throughout a given microfabrication process. For example, as discussed above, a 3D NAND memory device may have 128 or more layers of stacked films to create the memory device. This stack of layers imparts significant stress to the wafer, which may result in bowing that makes overlay errors problematic. Similarly, 3D logic has many layers and is expected to have a similar need to correct for wafer bow.

[0030] To this end, Figure 3 is a cross-sectional substrate segment showing structures or devices 399 formed on a surface, according to an embodiment of the present disclosure. In one embodiment, a wafer 305 includes a first surface 310 and a second surface 315. For example, the first surface 310 of the wafer can be a work surface on which target devices are fabricated. The second surface 315 can be a backside of the wafer. The devices 399 formed on the work surface 310 can be active devices, such as transistors or memory cells, or partially formed active devices. The wafer 305 can be received at a coating module of a coater / developer tool or other track-based tool.

[0031] FIG. 4 is a cross-sectional substrate segment showing a warpage-tuning stress film 325 (herein referred to as “stress film 325”) formed on the backside 315 of a wafer 305 according to an embodiment of the present disclosure. In one embodiment, the wafer 305 is flipped and the stress film 325 can be formed on the backside 315, although the wafer 305 need not be flipped. For example, the tool can include a system for vertical upward coating, spraying, or deposition. That is, the wafer 305 can remain on the track and the tool can form the stress film 315 on the backside 315 of the wafer by spray coating. In either case, the stress film 325 can be formed on the backside 315. The stress film 325 can be an organic film configured to release a stress tuning agent in response to actinic radiation. That is, the stress film 325 can include one or more photoacid generators, thermal acid generators, photoinitiators, photodestruct bases, etc. As noted above, the stressed film 325 may include various epoxy materials or resins or other organic materials that result in stress (tensile or compressive) in the stressed film 325 from curing in the presence of acids, bases, or radicals. For devices 399 disposed on the processing surface 310, a protective filler or protective film may be deposited or a carrier wafer may be attached to facilitate handling of the wafer 305.

[0032] It should be noted that the work side 310 and back side 315 are used herein to denote both sides of the wafer 305. In some microfabrication processes, a given wafer may have active devices or power delivery structures formed on both sides, in which case either the work side 310 or the back side 315 may receive the stress film 325 depending on the manufacturing process stage.

[0033] FIG. 5 is a cross-sectional substrate segment illustrating exposure of the stressed film 325 according to an embodiment of the present disclosure. In one embodiment, the stressed film 325 can be exposed to a pattern of actinic radiation that releases stress modifiers in the stressed film 325. This exposure step can be performed in a direct write module of a coater / developer tool or can be transferred to a separate or connected tool for exposure. The actinic radiation can be patterned such that coordinate locations on the backside 315 of the wafer 305 having the stressed film 325 receive more or less radiation. The resolution can depend on the particular lithography system selected to perform the exposure. The concentration of the released stress modifier at a given coordinate location can be based on the pattern of actinic radiation that illuminates the stressed film 325. This is represented by the more densely shaded portion of the stressed film 325 in FIG. 6.

[0034] FIG. 6 is a cross-sectional substrate segment showing the stressed film 325 after exposure, according to an embodiment of the present disclosure. In an embodiment, one or more curing steps may be performed, as described in FIGS. 2A-2C. The wafer 305 may be transferred to a bake / cure module of a coater / developer tool. The curing process may activate stress modifiers in the stressed film 325, resulting in a modulated stress in the stressed film 325 sufficient to modulate the bow of the wafer 305. For example, when exposed to light, a photoacid generator (PAG) (in a non-limiting example) may generate a photoacid, which upon baking and curing, may catalyze an epoxy cross-linking reaction. The reaction of cross-linking in the stressed film 325 results in stress relief. In some embodiments, imaging or exposure to a pattern of actinic radiation may directly modify the stressed film 325, thereby directly modifying or modulating the bow of the wafer 305. For example, stress may be relieved by imaging and removing bonding interactions, such as hydrogen bonding interactions, with a patterned exposure. That is, rather than inducing stress, the patterned exposure may relieve stress, for example, by activating a photoactive compound (PAC) and removing the inhibitory effect of a previously exposed PAC. The tailored stress may result from cross-linking, tailored bonding between species, or other entanglements. For example, the amount of cross-linking of the stressed film 325 via a stress modifier may correspond to the concentration of the released stress modifier at a given coordinate location based on the pattern of actinic radiation. Depending on the agent and film properties, the stress may be a tensile or compressive internal stress. The resulting stress in the stressed film 325 may then counteract the stresses induced in the wafer from, for example, microfabrication process steps. FIG. 6 shows a stressed film 325 having more or less stress depending on the coordinate location in the stressed film 325 based on the light projection pattern and one or more curing steps.

[0035] Thus, the warped wafer may be planarized with the stressed film 325 described herein. Programmable direct write patterns essentially activate (or pre-activate) the stress through cross-linking or chemical changes activated by specific wavelengths of light or electromagnetic energy, which may include longer wavelengths in the infrared (IR) or thermal range. IR wavelengths may be used to pattern the stressed film 325 through the wafer 305, i.e., through the wafer 305 exposed through the work surface 310. However, device fabrication on the work surface of the wafer may impair the ability to pattern the stressed film 325 through the wafer, especially at later stages of the device fabrication process. In some embodiments, the backside film may be activated using a wafer chuck with spatial temperature control, either in a track device or in device fabrication equipment. Stress activation may be tuned using different wavelengths of light based on the additives, rather than the polymers, in a given organic film. Thus, the stressed film 325 herein induces counteracting stress rather than releasing it as an etched film would, but an etching step is not required. In some embodiments, the wafer may be flipped over (such as the wafer of FIG. 5) so that the electromagnetic energy is patterned on the side to be imaged rather than through the backside 315.

[0036] As mentioned above, a developing process or step may be performed before curing. If a developing process is performed, a mismatch in the backside height of the wafer may occur. Thus, a filler may be deposited or formed on the backside stress film 325. The backside filler may then be planarized before turning the wafer 305 back over for further fabrication and processing. Otherwise, the film height mismatch at a particular location may itself cause a shape defect in the wafer 305. However, this should further highlight the advantage of direct write control, where no developing process is required and a kind of film height mismatch does not occur. Direct write creates a flat film, and although bowing may be induced, the film remains flat.

[0037] In one embodiment, two or more stress films 325 may be deposited. Each given film may be activated by the same or different wavelengths. This multi-layer process may be used to create cumulative or differential stress. For lower resolution wafer bow correction, the films herein may be activated simply by targeted or patterned heating without a photoactivation pattern step (i.e., global bow relaxation). Zone-based heating, or mask-based heat curing, or microwave heating may result in site-specific cross-linking. In this case, either photoacid generators (PAGs) or thermal acid generators (TAGs) may be used, since most PAGs can function as TAGs at sufficiently high temperatures.

[0038] In one embodiment, incorporating a stress film on the backside may result in tradeoffs that may impact device yield. With co-optimization of design techniques where a multi-directional actuation stress film is planned to be incorporated on the frontside, the benefits of the technology may be realized without the tradeoffs. In such implementations, the stress film 325 may be formed on the processing surface 310, such as in the areas between devices on the wafer 305, along the periphery of the processing surface 310, or even on top of the devices.

[0039] The techniques herein can affect wafer bow of hundreds of microns, which is sufficient to counter wafer bow and warp observed in wafers during semiconductor manufacturing. The resulting bow adjustments herein can be primary and secondary bowing corrections, such as saddle bow. The techniques herein can be used throughout the semiconductor manufacturing process. For example, after the initial bow is corrected with the films herein, further processing can be performed. This further processing can then result in further warp. At this point, a second bow adjustment film can be added and patterned before curing. Alternatively, after stripping the first bow adjustment film, the wafer warp is measured a second time, and then a subsequent bow adjustment is deposited and patterned according to the second wafer bow measurement.

[0040] FIG. 7 is a flow chart of a method 700 for processing a substrate according to an embodiment of the present disclosure.

[0041] A wafer 305 may be received by the tool in step 705. The wafer 305 includes a first surface 310 (working side 310) and a second surface 315 (backside 315).

[0042] In step 710, a stressed film 325 may be formed on the backside 315 of the wafer 305. The stressed film 325 may include a stress modifier, such that the stressed film 325 is sensitive to a predetermined wavelength of actinic radiation.

[0043] In step 715, the stressed film 325 may be exposed to a pattern of actinic radiation at a predetermined wavelength. The stressed film 325 may be configured to release a stress modulating agent at locations along the stressed film 325 exposed to the pattern of actinic radiation. A concentration of the released stress modulating agent may correspond to the pattern of actinic radiation.

[0044] In step 720, a curing process may be performed that activates the released stress adjusting agent and induces stress changes in the stress film 325, adjusting the bow of the wafer 305 and making the wafer 305 closer to flat.

[0045] In step 725, optionally, a developing process may be performed before curing.

[0046] In the above description, specific details have been described, such as the specific geometry of the processing system and a description of the various components and processes used. However, it should be understood that the techniques herein may be implemented in other embodiments that differ from these specific details, and that such details are for illustrative purposes and not for limiting purposes. Several embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, for illustrative purposes, specific numbers, materials, and configurations have been described to ensure a thorough understanding. Nevertheless, several embodiments can be implemented without such specific details. Components having substantially the same functional structure are labeled with similar reference numerals, and therefore any redundant description may be omitted.

[0047] To facilitate understanding of various embodiments, various techniques have been described as multiple discrete operations. The order of description should not be construed as implying that these operations are necessarily order dependent. In fact, these operations need not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. In additional embodiments, various additional operations may be performed and / or described operations may be omitted.

[0048] As used herein, "substrate" or "target substrate" refers generally to an object to be processed according to the present invention. The substrate may include any material portion or structure of a device, particularly a semiconductor device or other electronic device, and may be, for example, a base substrate structure such as a semiconductor wafer, a reticle, or a layer on or overlying the base substrate structure, e.g., a thin film. Thus, the substrate is not limited to any particular base structure, underlayer, 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. Although the description may refer to a particular type of substrate, this is for illustrative purposes only.

[0049] Those skilled in the art will also appreciate that many variations can be made to the operation of the techniques described above and still achieve the same objectives of the invention. Such variations are intended to be encompassed within the scope of the present disclosure. Accordingly, the above description of embodiments of the invention are not intended to be limiting. Rather, limitations to embodiments of the invention are presented in the following claims.

Claims

1. 1. A method of processing a substrate, the method comprising: forming a warpage adjusting stress film on the backside of the wafer; the wafer includes a work surface and a back side opposite the work surface; the warpage adjusting stress film includes a stress adjusting agent; the warp-tuning stress film is sensitive to a predetermined wavelength of actinic radiation; Steps and exposing the warp-tuning stress film to a pattern of actinic radiation at the predetermined wavelength; the warp-adjusted stress film is configured to release the stress-adjusting agent at locations along the warp-adjusted stress film that are exposed to the pattern of actinic radiation; a concentration of the released stress modifier corresponding to the pattern of the actinic radiation; Steps and carrying out a curing process; the curing step activates the released stress adjusting agent and induces a stress change in the warpage adjusting stress film; the stress change adjusts the warpage of the wafer; The material of the warpage adjusting stress film is at least one selected from the group consisting of epoxy acrylate and epoxy novolac. Steps and A method comprising:

2. The curing step activates the released stress modifier. creating cross-links in the warp-adjusting stress film based on the pattern of actinic radiation; The method of claim 1 further comprising:

3. a photoacid generator, in which the warpage adjusting stress film generates an acid in response to the predetermined wavelength of the actinic radiation; The method of claim 1 , comprising:

4. a photoinitiator, wherein the warpage adjusting stress film generates radicals in response to the predetermined wavelength of the actinic radiation; The method of claim 1 , comprising:

5. forming the warp adjusting stress film, exposing the warp adjusting stress film to the pattern of actinic radiation, and performing the curing step are performed without introducing a developer to the wafer. The method of claim 1.

6. The step of performing the curing process comprises: applying heat to the wafer until a predetermined degree of cross-linking occurs within the warp-engineered stress film; The method of claim 1 further comprising:

7. exposing the warp-adjusting stress film to a pattern of actinic radiation; applying actinic radiation at an intensity based on the selected amount of warpage adjustment to be achieved; The method of claim 1 further comprising:

8. The stress change adjusts the warpage of the wafer, Reducing the warpage value of the wafer on the processing surface, thereby reducing the curvature of the wafer compared to before depositing the warpage adjusting stress film; The method of claim 1 further comprising:

9. The warpage adjusting stress film contains a photobase generator. The method of claim 1.

10. The method further comprises: depositing a second warpage adjusting stress film on the backside of the wafer; the second warpage adjusting stress film includes a second stress adjusting agent; the second warpage adjusting stress film is sensitive to a second predetermined wavelength of the actinic radiation; Steps and exposing the second warpage adjusting stress film to a second pattern of actinic radiation; Including, the curing step activates the released second stress adjusting agent to induce the stress change in the warpage adjusting stress film; the stress change adjusts the bow of the wafer. The method of claim 1.

11. The method further comprises: depositing a second warpage adjusting stress film on the backside of the wafer; the second warpage adjusting stress film includes a second stress adjusting agent; the second warpage adjusting stress film is sensitive to a second predetermined wavelength of the actinic radiation; Steps and exposing the second warpage adjusting stress film to a second pattern of actinic radiation; performing a second curing step; the second curing step activates the released second stress adjusting agent to induce a stress change in the warpage adjusting stress film; The stress change adjusts the warpage of the wafer. Steps and The method of claim 1 , comprising:

12. The first predetermined wavelength and the second predetermined wavelength are different. The method of claim 11.

13. the pattern of actinic radiation is based on a bow-adjusted stress map for the wafer. The method of claim 1.

14. the warpage-adjusted stress map indicates relaxing stress values ​​across coordinate positions along the backside of the wafer. The method of claim 1.

15. The warpage-tuning stress film is deposited by spin-on deposition. The method of claim 1.

16. the pattern of actinic radiation is provided by a direct write lithography system. The method of claim 1.

17. the pattern of actinic radiation is provided by a mask-based lithography system. The method of claim 1.

18. 1. A method of processing a substrate, the method comprising: forming a first warpage adjusting stress film on the backside of the wafer; the wafer includes a work surface and a back side opposite the work surface; the first warpage adjusting stress film is configured to release a first stress adjusting agent in response to actinic radiation having a first predetermined wavelength; Steps and forming a second warpage adjusting stress film on the first warpage adjusting stress film; the second warp adjusting stress film is configured to release a second stress adjusting agent in response to the actinic radiation having a second predetermined wavelength; Steps and exposing the first warp adjusting stress film and the second warp adjusting stress film to a first pattern of actinic radiation at the first predetermined wavelength; the first warp adjusting stress film is configured to release the first stress adjusting agent at locations along the first warp adjusting stress film exposed to the first pattern of actinic radiation; a concentration of the released first stress modulating agent corresponds to the first pattern of the actinic radiation; Steps and exposing the first warp adjusting stress film and the second warp adjusting stress film to a second pattern of actinic radiation at the second predetermined wavelength; the second warp adjusting stress film is configured to release the second stress adjusting agent at locations along the second warp adjusting stress film exposed to the second pattern of actinic radiation; a concentration of the released second stress modulating agent corresponds to the second pattern of the actinic radiation; Steps and carrying out a curing process; the curing step activates the released first stress modifier and the released second stress modifier; the curing step causes a first stress change in the first warpage adjusting stress film; generating a second stress change in the second warpage adjusting stress film; the first stress change and the second stress change together adjust the bow of the wafer. Steps and Including, The material of the warpage adjusting stress film is at least one selected from the group consisting of epoxy acrylate and epoxy novolac. method.

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