Influence function-based mitigation of substrate deformations with thin film deposition and ion implantation

Abstract

The disclosed systems and techniques relate to correcting out-of-plane (OPD) deformation of a substrate by: depositing a stress compensation layer (SCL) on the substrate; a profile of the OPD of the substrate is obtained using optical inspection data. The technique further includes obtaining a data set having a representation of an impact function on the substrate, the impact function characterizing a deformation response of the substrate caused by a punctiform mechanical impact. The technique further includes performing a regression calculation to determine a distribution of stress mitigation illumination of the SCL mitigating the OPD of the substrate based at least on the profile of the OPD of the substrate and the influence function. The technique further includes performing stress relief irradiation of the SCL using the determined profile of stress relief irradiation.

Description

Technical Field

[0001] This disclosure relates to semiconductor fabrication, including the fabrication of wafers. Background Art

[0002] Modern semiconductor components (such as processing circuits, memory components, photodetectors, solar cells, light-emitting semiconductor components and the like) are typically manufactured on silicon wafers (or other suitable substrates). The wafer may undergo many processing operations, such as physical vapor deposition, chemical vapor deposition, etching, photomasking, polishing and / or various other operations. In order to continuously reduce the cost of semiconductor components, multilayer stacks of bare crystals, insulating films, patterned and / or doped semiconductor films and / or other features are typically deposited on a single wafer to produce high aspect ratio components, such as those used in three-dimensional flash memory components and other applications. The processes of depositing, patterning, etching, polishing, etc. of the multilayer structure stack typically result in significant stress being applied to the underlying wafer. Such stress can cause both out-of-plane and in-plane distortions of the features supported by the wafer. These distortions can cause misalignment of the deposited features and can significantly reduce the quality of the manufactured component. Summary of the Invention

[0003] In one embodiment, disclosed is a method for correcting out-of-plane deformation of a substrate, the method comprising depositing a stress-compensating layer (SCL) on the substrate. The method further comprises obtaining a profile of the out-of-plane deformation (OPD) of the substrate using optical inspection data. The method further comprises obtaining, by a processing device, a dataset comprising a representation of an influence function for the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact. The method further comprises performing a regression calculation to determine a profile of stress-relief irradiation of the SCL to mitigate the OPD of the substrate based on at least the profile of the OPD of the substrate and the influence function. The method further comprises performing stress-relief irradiation of the SCL using the determined profile of the stress-relief irradiation.

[0004] In another embodiment, disclosed is a system comprising a memory and a processing device communicatively coupled to the memory for depositing a stress-relief layer (SCL) on a substrate. The processing device is further configured to obtain a profile of an optical displacement device (OPD) of the substrate using optical inspection data. The processing device is further configured to obtain a dataset comprising a representation of an influence function for the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact. The processing device is further configured to perform a regression calculation to determine a profile of stress-relief treatment of the SCL to reduce the OPD of the substrate based on at least the profile of the OPD of the substrate and the influence function. The processing device is further configured to perform stress-relief treatment of the SCL using the determined profile of the stress-relief treatment.

[0005] In another embodiment, disclosed is a system comprising a memory and a processing device communicatively coupled to the memory. The processing device is configured to deposit a stress-relief layer (SCL) on a substrate and obtain a profile of an optical path length (OPD) of the substrate using optical inspection data. The processing device is configured to obtain a dataset comprising a representation of an influence function for the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact. The processing device is configured to perform a regression calculation to determine a profile of stress-relief treatment of the SCL to reduce the OPD of the substrate based on at least the profile of the OPD of the substrate and the influence function. The processing device is further configured to perform stress-relief treatment of the SCL using the determined profile of the stress-relief treatment.

[0006] In yet another embodiment, disclosed is a non-transitory computer-readable memory having instructions stored thereon that, when executed by a processing device, cause the processing device to perform operations comprising: depositing a SCL on a substrate. The operations further comprise: obtaining a profile of an optical displacement device (OPD) of the substrate using optical inspection data. The operations further comprise: obtaining a dataset comprising a representation of an influence function for the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact. The operations further comprise: performing a regression calculation to determine a profile of stress-relief irradiation of the SCL to mitigate the OPD of the substrate based at least on the profile of the OPD of the substrate and the influence function. The operations further comprise: performing stress-relief irradiation of the SCL using the determined profile of the stress-relief irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present disclosure can be more fully understood from the following detailed description and accompanying drawings of various embodiments of the present disclosure.

[0008] Figure 1A-1EA process for stress correction of a backside deposited film using additional ion implantation is schematically illustrated in accordance with at least one embodiment.

[0009] Figure 2 An example Zernike polynomial decomposition of an actual deformation of a wafer (upper left) in arbitrary units is shown to decompose it into parabolic bow deformation (upper right), saddle deformation (lower left), and residual deformation (lower right), in accordance with at least one embodiment.

[0010] Figure 3 An example wafer is shown for use in accordance with at least one embodiment. Figure 1A-1E Disclosed process for stress and deformation relief.

[0011] Figure 4 An example profile of a Gaussian ion beam that may be used for stress and deformation mitigation in a wafer is shown in accordance with at least one embodiment.

[0012] Figure 5 An example silicon wafer having a silicon nitride film deposited thereon and having a saddle-shaped deformation is shown in accordance with at least one embodiment.

[0013] Figure 6 is a flow chart illustrating an example process for impact function-based mitigation of wafer deformation in accordance with at least one embodiment.

[0014] Figures 7A-7C Ion implantation using a spot beam centered around a series of points along a radial direction is shown in accordance with at least one embodiment.

[0015] Figure 8 Depicted are simulation results of deformation caused by an ion implantation beam directed to different locations on a wafer / thin film structure, in accordance with at least one embodiment.

[0016] Figure 9A An ion implantation system capable of performing ion implantation into a stress-compensating layer in accordance with at least one embodiment is schematically illustrated.

[0017] Figure 9B According to at least one embodiment, Figure 9A The ion implantation system delivers ions to the wafer at any incident angle.

[0018] Figure 10 A block diagram of an example computer system capable of supporting operations of the present disclosure in accordance with at least one embodiment is depicted. DETAILED DESCRIPTION

[0019] The prior art includes a variety of approaches to addressing wafer deformation. For example, a deformed (warped) wafer, with various films and features deposited on one side (herein referred to as the front, top, or primary side), can be coated on the other side (herein referred to as the backside or bottom side) with a film that applies compressive or tensile stress to the wafer. Such backside-deposited deformation-correcting films (herein also referred to as stress-compensating layers) typically apply a uniform (or global) stress across the entire wafer and are unable to compensate for localized stress modulation and / or anisotropic stress. Additional correction can be achieved by implanting ions into the stress-compensating layer (e.g., bombarding the stress-compensating layer with an ion beam) to adjust the stress in the stress-compensating layer, thereby further mitigating deformation in the underlying wafer.

[0020] As used herein, "wafer" refers to any substrate or material surface formed on a substrate on which thin film processing is performed during the manufacturing process. For example, depending on the application, wafer surfaces on which processing may be performed include materials such as silicon, silicon oxide, silicon nitride, strained silicon, silicon-on-insulator structures, carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other material (e.g., metals, metal nitrides, metal alloys, and other conductive materials). Wafers include, but are not limited to, semiconductor wafers. In some cases, wafers may include plastic substrates. Wafers may be exposed to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam cure, and / or bake the substrate surface. In addition to performing thin film processing directly on the surface of the wafer itself, any of the disclosed thin film processing steps may also be performed on an underlying layer formed on the wafer, as disclosed in more detail below, and the term "wafer surface" is intended to include such underlying layers as indicated by the context. Thus, for example, if a thin film / layer or portion of a thin film / layer has already been deposited on the wafer surface, the exposed surface of the newly deposited thin film / layer becomes the wafer surface. In some embodiments, the thickness of the wafer is in the range of 0.25 mm to 1.5 mm, or in the range of 0.5 mm to 1.25 mm, or in the range of 0.75 mm to 1.0 mm, or thicker. In some embodiments, the diameter of the wafer is about 10 cm, 20 cm, 30 cm or more.

[0021] Stress compensation layers deposited by ion implantation are used to correct uniform and isotropic stress (σ xx ≈σ yy ) can be quite efficient. On the other hand, the stress (σ) that varies with position x,y on the wafer can be mitigated. jk (x,y)), anisotropic stress (σ xx ≠σ yy ) or both is a more challenging problem. Certain patterns may result in compressive stress along one direction (e.g. σ xx<0), and tensile stress (σ yy >0), resulting in saddle-shaped wafers, such as Figure 5 Such saddle-shaped features may appear, for example, in material stacks with directional patterning (e.g., the patterning of word lines in flash memory devices). Correcting such anisotropic saddle-shaped deformations in wafers remains a difficult task.

[0022] Aspects and embodiments of the present disclosure address these and other challenges of modern semiconductor manufacturing technology by providing systems and techniques that can mitigate non-uniform and / or anisotropic stresses and deformations (e.g., out-of-plane deformations) in a wafer. In some embodiments, the deformation of the wafer can be measured (e.g., using optical measurement techniques), and the parameters of the stress-compensating layer (e.g., layer material, thickness, etc.) can be determined so that the sign of the stress is the same across the entire wafer. For example, if the deformation of the wafer is concave, the parameters of the stress-compensating layer can be selected to overcorrect the wafer into a convex shape. An ion implantation map (local dose distribution of the ion implant) n(x,y) can then be calculated to reduce the local stress in the wafer to a level that converts the convex shape into a flat (or nearly flat) shape. As disclosed herein, the implantation map n(x,y) can be calculated using an influence function G(x,y; x',y') that characterizes the response (e.g., deformation) of the wafer at a point (x,y) of the wafer due to a point force applied at the point (x',y') of the wafer. In some embodiments, the influence function G(x, y; x′, y′) (also known as Green's function) can be determined based on computational simulations or analytical calculations. In some embodiments, the influence function can be determined based on one or more experiments that can include performing ion implantation into a thin film deposited on a reference wafer.

[0023] In one embodiment, the vertical profile z=h(r,φ) of the wafer deformation can be measured using optical metrology techniques. For example, optical interferometry can be used to obtain an interference pattern of the profile h(r,φ). The wafer profile h(r,φ) can then be represented by a plurality of parameters that qualitatively and quantitatively characterize the geometry of the wafer deformation. In some embodiments, the wafer profile can be represented using a set of Zernike (or a similar set of) polynomials,

[0024]

[0025] where r is the radial coordinate and φ is the polar coordinate in the (average) plane of the wafer. The successive coefficients A1, A2, A3, A4, ... represent the weighting of certain geometrical features of the wafer (element deformations) described by the corresponding Zernike polynomials Z1(r,φ), Z2(r,φ), Z3(r,φ), Z4(r,φ), ... . The first three coefficients are less important, since they describe a uniform movement of the wafer (coefficient A1, associated with the polynomial Z1(r,φ) = 1), a deformation-free x-tilt equivalent to a rotation about the y-axis (coefficient A2, associated with the polynomial Z2(r,φ) = 2rcosφ), and a deformation-free x-tilt equivalent to a rotation about the x-axis (coefficient A3, associated with the polynomial Z3(r,φ) = 2rsinφ), which can be eliminated by realigning the coordinate axes. The fourth coefficient A4 is associated with The fifth coefficient A5 and the sixth coefficient A6 are related to and The polynomials are associated and characterize saddle-type deformations. The A5 coefficient characterizes saddle shapes that bend upward (A5>0) or downward (A5<0) along the diagonal y=x and downward (A5>0) or upward (A5<0) along the diagonal y=-x. The A6 coefficient characterizes saddle shapes that bend upward (A6>0) or downward (A6<0) along the x-axis and downward (A6>0) or upward (A6<0) along the y-axis. Higher coefficients A7, A8, etc. characterize that the wafer deformation h(r,φ) changes increasingly rapidly along the radial direction, along the azimuthal direction, or both, and together represent the residual deformation. Figure 2 An example Zernike polynomial decomposition 200 of an actual deformation h(r,φ) of a wafer (upper left) in arbitrary units is shown to decompose the deformation into a parabolic bow deformation A4Z4(r,φ) (upper right), a saddle deformation A5Z5(r,φ)+A6Z6(r,φ) (lower left), and a residual deformation h res (r,φ)(lower right).

[0026] In some embodiments, the thickness d of the stress-compensating film may be selected based on the value of the parabola bow coefficient A4. Figure 1A-1E A process for stress correction of a backside deposited film using additional ion implantation is schematically illustrated in accordance with at least one embodiment. Figure 1A A wafer 102 is depicted having deformations, which may include parabolic bow deformation (having a negative coefficient A4 < 0) and other deformations, such as saddle deformation and residual deformation (both are shown in FIG. Figure 1A-1E(not shown in the figures). Wafer 102 has a front side 104 and a back side 106. Any number of features (e.g., deposited and / or etched patterns), bare die, photomasks, and / or any other structures may be deposited on or etched in front side 104. In some embodiments, back side 106 may be free of deposited / etched features / structures. In some embodiments, back side 106 may also have one or more deposited / etched features / structures. Figure 1B The schematic diagram shows the deposition of a stress-compensating layer on the backside of wafer 102. In some embodiments, stress-compensating layer 108 can include one or more thin films of different materials. The thickness of individual films can be in the range of 10 to 200 nanometers, or in the range of 20 to 180 nanometers, or in the range of 30 to 160 nanometers, or in the range of 40 to 140 nanometers, or greater. The total thickness of the stress-compensating layer can be up to several micrometers or even thicker. In some embodiments, stress-compensating layer 108 is deposited at a temperature in the range of 100°C to 500°C or higher.

[0027] The material (type) of the stress compensating layer 108 can be selected based on the sign of the coefficient A4. For example, for negative bow, A4 < 0, and the stress compensating layer 108 can be selected to have a compressive stress after deposition while leaving the bottom surface of the wafer with a tensile stress (e.g., Figure 1A-1E For a silicon wafer, this film may be a silicon nitride (Si3N4) film. Conversely, for a positive bow, A4>0, and the stress compensation layer 108 may be selected to have a tensile stress ( Figure 1A-1E (not shown). The stress-compensating layer 108 can be deposited using any suitable deposition technique, including physical vapor deposition (e.g., sputtering), chemical vapor deposition (e.g., plasma-assisted deposition), epitaxy, lift-off, and / or the like. Deposition can be performed at room temperature or at a temperature different from room temperature (e.g., elevated temperature). In some embodiments, the thickness d of the stress-compensating layer 108 can be selected to overcorrect deformation to a certain extent, e.g., Figure 1C As shown, the negative parabolic bow becomes a positive parabolic bow. Thickness-dependent parabolic bow correction A corr (d) Change the wafer deformation from h(r,φ) to h corr (r,φ):

[0028] h corr (r,φ)=h(r,φ)+A corr (d)·Z4(r,φ).

[0029] The overcorrection is selected in conjunction with the implant species, energy, and dose to ensure maximum benefit from stress compensation. The overcorrection allows the combined structure of the wafer 102 and the stress compensating layer 108 to be susceptible to further control of stress (and thus to wafer deformation). corr Further control of (r,φ). Figure 1D As shown, an ion beam implanter 110 can generate an ion beam 112 that strikes the stress-compensating layer 108 and deposits ions therein. The ion beam 112 can carry silicon ions, phosphorus ions, argon ions, neon ions, xenon ions, krypton ions, and / or the like. In some embodiments, the energy and type of ions in the ion beam 112 can be selected to confine the implanted ions to the volume of the stress-compensating layer 108 and prevent the ions from reaching the wafer 102. Ions retained in the stress-compensating layer 108 can generate substitutional defects therein. Furthermore, the ions can also leave traces of vacancy defects along their propagation paths in the stress-compensating layer 108. The substitutional defects and / or vacancies modify (e.g., reduce) the stress in the stress-compensating layer 108 and can reduce the degree of stress overcorrection caused by thin film deposition. This results in a flattening of the combination of the wafer 102 and the stress-compensating layer 108.

[0030] While the stress mitigating beam used to modify stress in the stress-compensating layer 108 is referred to as an ion beam (e.g., ion beam 112) for purposes of detail, throughout this disclosure, stress mitigating beams (irradiation) may include other species (e.g., electrons), electromagnetic waves (e.g., ultraviolet light, visible light, infrared light, etc.), and / or suitable combinations thereof. The stress mitigating beam impacts the stress-compensating layer 108 and alters the bonding network of the stress-compensating layer 108. For example, a low-energy stress mitigating beam may interact with surface atoms of the stress-compensating layer 108, for example, removing some of the surface atoms, thereby effectively etching the surface region of the stress-compensating layer 108. The effectiveness of this etching can be controlled by selecting the ion species / radicals / ambient gas. In another example, a high-energy stress mitigating beam may deposit ions within the stress-compensating layer 108. The ions and / or photons may disrupt bonds in the bonding network (or lattice) of the stress-compensating layer 108, thereby forming vacancies therein, which may further induce annealing due to localized heating, UV curing, and / or other effects.

[0031] In some embodiments, simulations (performed in more detail below) can be used to estimate the deformation h based on the correction. corr The local value of (r, φ) determines the number of ions deposited per small area of ​​the wafer ΔA = ΔxΔy ΔN i The corrected deformation may include saddle deformation, residual deformation, and a parabolic bow-shaped deformation portion A that has been overcorrected by the deposition of the stress compensation layer 108. corr(d) + A4. The desired local density of ions n(x, y) = ΔN can be delivered by controlling the scanning speed v of the ion beam 112. i / ΔxΔy. In some embodiments, the profile of the ion beam 112 can be approximated by a Gaussian function, for example, ion flux j(ρ)=j0exp(-x 2 / a 2 -y 2 / b 2 ), where x and y are Cartesian coordinates, j0 is the maximum ion flux at the beam center, and a and b are the characteristic spread of the beam along the x and y axes, respectively. Correspondingly, a point at a distance y relative to the beam center path receives an ion dose comprising the following number of ions:

[0032]

[0033] Correspondingly, by reducing the scanning speed v, the number of ions received by various regions of the stress compensation layer 108 can be increased, and vice versa. In addition, the ion beam 112 can be scanned multiple times with different offsets y, so that various points of the stress compensation layer 108 are scanned with different coefficients. For example, after n passes through the ion beam implanter 110 (each at a different distance y from the center of the ion beam 112), the coefficients can be averaged to a target dose. k At the corresponding speed v k For area ΔxΔy), the total ion dose received by this area will be

[0034]

[0035] like Figure 1E As shown, the implanted layer 114 formed as part of the stress compensating layer 108 significantly reduces deformation of the wafer 102, particularly the saddle and residual portions thereof.

[0036] Figure 3 An example wafer is shown for use in accordance with at least one embodiment. Figure 1A-1E The disclosed process reduces stress and deformation by 300. Figure 3 As shown, a 30 cm silicon wafer 102 having a maximum negative strain of -75.0 μm is first overcorrected to a maximum strain of +83.5 μm using a silicon nitride tensile stress compensating layer 108. The stress in the stress compensating layer 108 is then reduced by forming an implanted layer 114 using an ion beam, resulting in a final maximum strain of +15.4 μm. Figure 4 An example profile 400 of a Gaussian ion beam 112 that may be used for stress and deformation mitigation in a wafer is shown in accordance with at least one embodiment.

[0037] Figure 1- Figure 3 The techniques shown for strain and deformation mitigation can also be applied to wafers with complex deformations, where the stress tensor components σ xx and σ yy have different signs, resulting in a saddle-shaped deformation of the wafer. Figure 5 An example wafer 500 (e.g., a silicon wafer with a silicon nitride film deposited thereon) having saddle-shaped deformation is shown in accordance with at least one embodiment. As seen in the cross-sectional xz view 502, the stress component σ in the wafer (top layer) xx may be lower than the stress component σ in the thin film (bottom layer) deposited on the back side of the wafer xx In contrast, as shown in the cross-sectional yz view 504, the stress component σ in the wafer yy may be higher than the stress component σ in the film yy In some embodiments, the stress state in the wafer can be represented by a position-dependent stress tensor that can be approximated as:

[0038]

[0039] This structure of the stress tensor is usually a good approximation because the wafer is generally in pure bending and is independent of the shear stresses represented by the off-diagonal terms in the stress tensor. Correcting for the saddle shape requires special care in the dose map calculation and optimization to ensure that no additional residual terms are introduced into the wafer.

[0040] Figure 6 6 is a flow chart illustrating an example process 600 for mitigating wafer deformation based on an influence function, according to at least one embodiment. Process 600 can be performed using a semiconductor manufacturing system comprising one or more processing chambers, such as a deposition chamber, a plasma chamber, an etch chamber, a polishing chamber, a thin film removal chamber, a beam irradiation chamber, an optical inspection chamber, and / or the like. The processing chambers can be coupled to one or more transfer chambers, which can be equipped with robots for transferring wafers, such as moving wafers into and out of the processing chambers. The transfer chambers can further be coupled to a load lock chamber (front-end interface), which can be coupled to one or more front-opening unified pods (FUPs) that hold bare wafers, processed wafers, partially processed wafers, and / or the like. The operations performed by the semiconductor manufacturing system, including any, some, or all of the operations of process 600, can be executed in response to instructions issued by a suitable computing device having processing logic and memory for storing instructions.

[0041] At block 610, process 600 includes measuring the shape of a wafer, such as a surface of the wafer (eg, top or bottom surface) as a radius vector The displacement of the function The displacement can be expressed using any suitable set of in-plane coordinates, such as polar coordinates (h W (r,φ)), Cartesian coordinates (h W (x,y)) or any other coordinates. In some embodiments, the wafer deformation can be represented by a decomposition of the determined shape by a suitable set of basis functions (e.g., Zernike polynomials) or some other set of polynomials. Wafer deformation It may be caused by the following: effective deformation pressure applied to the top surface of the wafer due to local stress caused by patterning / etching the wafer, depositing one or more thin films on the top surface of the wafer, and / or performing any other technological operations on the wafer The relationship between wafer deformation and effective deformation pressure can be described by the classic plate equation:

[0042]

[0043] Where t is the thickness of the wafer, D = Et 3 / 12(1-ν 2 ) is the flexural rigidity of the wafer; E and ν are Young's modulus and Poisson's ratio of the wafer material, respectively; is the plane Laplacian operator. Wafer deformation This is accompanied by a plane stress which, at the bottom surface of the wafer, is:

[0044]

[0045] Plane stress can be negative (compressive) in certain areas of the wafer Can be positive (tensile) in other areas of the wafer

[0046] At block 620, the determined deformation may be used To identify the properties (e.g., material and thickness) of the target stress compensating film to be deposited on the wafer. In some embodiments, the film can be selected so that the stress σ in the new wafer / film structure is WF Has a definite sign. Figure 3 In the example, the bottom side of the Si wafer 102 experiences a compressive stress, such as σ WF<0. The stress compensating layer 108 may be selected to reverse the sign of the wafer stress at the bottom side of the wafer 102 and make the wafer stress tensile (σ WF >0). More specifically, the stress compensating film (layer) exerts an effective local pressure This causes the chip to change shape in

[0047]

[0048] The material and thickness of the stress compensation layer 108 may be selected so that is large enough (in absolute terms) to ensure

[0049]

[0050] The benefit of this is that ion implantation can reduce the amount of stress in the film, whereas reversing the sign of the tension in the film with ions can be difficult.

[0051] exist Figure 6 At block 630, process 600 may include depositing a thin film (stress compensating layer) of a selected material and thickness on the wafer. In some embodiments, process 600 may include re-measuring 640 (e.g., using optical interferometry) the wafer deformation modified by the thin film. In some implementations, the value Estimating modified wafer deformation Rather than performing a remeasurement. In some embodiments, It can have a uniform value over the entire area of ​​the wafer (this value is caused, for example, by a deposited film of uniform thickness): P F = Cd, where d is the thickness of the film and C is an empirically determined coefficient that depends on the specific material type. Different materials can be characterized by coefficients C with different magnitudes and signs.

[0052] Measured (and / or estimated) deformation of the wafer Can be used to determine stress relief and reduce the deformation to zero (or close to zero) Ion implantation dose map Uneven ion implantation can lead to a reduction in the uniform pressure applied to the film, reducing the amount Determined by the local ion dose:

[0053]

[0054] where K is a constant that depends on the ion type, ion energy, ion implantation angle, and / or other parameters of the ion implantation process. Under ideal conditions, the ion implantation correction Can be selected to make the total pressure vanish Due to the effective deformation pressure is difficult to estimate, so it can be based on the deformation pressure exerted by the various features patterned on the wafer and the deposited film. Deformation caused To more efficiently determine ion implantation corrections In detail, the compensation deformation h WL Ion implantation correction for (x,y) Follow the following procedure:

[0055]

[0056] Block 635 may include calculating the influence function (Green's function) for the classical plate equation:

[0057]

[0058] Where δ() is the Dirac delta-function. According to its definition, the influence function characterizes the effect of a wafer (e.g., an undeformed wafer) at point Point Once the influence function is known, the deformation caused by the ion implantation correction can be determined by integrating it over the entire area of ​​the wafer. Deformation caused by:

[0059]

[0060] As described below in connection with block 650, the solution to this equation can determine the local ion density for the ion implantation.

[0061] In some embodiments, the integral can be calculated over an area of ​​the wafer of size Δl x ×Δl y For example, for a wafer with a diameter of 30 cm, the discrete fragments can be Δl x =Δl y = 5mm, 10mm, 12mm and / or similar sizes. In various embodiments, the influence function is defined in Cartesian coordinates And the integration is also performed in Cartesian coordinates. In some embodiments, the influence function (and deformation) can be defined in arbitrary other coordinates, such as polar coordinates. And the integration metric is also adjusted accordingly (dx′dy′→r′dr′dφ′).

[0062] Influence function Various techniques can be used to determine. In one embodiment, as shown in block 615, the influence function This can be determined using experimental data. For example, a point ion beam of reference intensity (flux) j(x-x0, y-y0) can be centered at different points (x0, y0) of a thin film of known thickness on a reference wafer (e.g., an undeformed wafer) for a reference time Δt (thus depositing 100 Å per unit film area). ions), and the resulting deformation change Δh(x,y) caused by the beam can be measured. In some embodiments, the point beam can be a Gaussian beam (j(x-x0,y-y0)=j0exp(-(x-x0) 2 / a 2 -(y-y0) 2 / b 2 ), with an extent a along the x-axis and an extent b along the y-axis (in some embodiments, the beam profile may be symmetric (a=b)). ​​Different points on the radius of the wafer may be probed, for example a set of points (x0,y0) = (0,0); (l,0); (2l,0), etc., which may be separated by a spacing l along a given radial direction (e.g., the x-axis in this example). The spacing l may be related to the size of the discrete fragments (e.g., Δl x and / or Δl y ) of the same order of magnitude. In some embodiments, the spacing l can be position-dependent, for example, a larger spacing l (lower resolution) is used to detect wafer deformation caused by a spot beam 112 centered near the middle of the wafer / film (near the center of the wafer / film), and a smaller spacing l (higher resolution) is used to detect wafer deformation caused by a spot beam 112 centered near the edge of the wafer / film.

[0063] Figures 7A-7C FIG. 1 shows ion implantation using a spot beam 112 centered at a series of spots 702, 704, 706 along a radial direction 710, in accordance with at least one embodiment. The spot beam may have a Gaussian shape 712 or any other suitable shape. The deformation caused by the point beam 112 at and applied to the film for a duration of Δt can be expressed by the following influence function:

[0064] Δh(x,y;x0,y0)=KΔt∫∫dx′dy′G(x,y;x′,y′)j(x′-x0,y′-y0)

[0065] A discretized version of this equation (replacing the integral with ) can be used to determine the influence function G(x,y; x′,y′). More specifically, the measured deformation Δh(x,y; x0,y0) (schematically illustrated by the heat map 714) represents the experimental input, the shape of the ion implantation beam j(x′-x0,y′-y0) can be a known fixed input (e.g., an input determined by the settings of the ion implantation apparatus), and the influence function G(x,y; x′,y′)G(x,y; x′,y′) can be obtained using an inverse matrix multiplication technique. In some embodiments, the points 702, 704, 706, etc., at which the spot beam 112 is centered, can be located along the same radial line, and the axial symmetry of the wafer 102 can be used to determine the influence function for other points. More specifically, the influence function can then be assumed to be the same (axial symmetry) for other locations of the source point. Expressed in polar coordinates, this axial symmetry implies that the influence function G(r,φ-φ′;r′) depends on the distance to the “source point” and "destination point" In some embodiments, since a real wafer (and / or wafer / film structure) may be slightly asymmetric, the deformation caused by applying the spot beam 112 along different directions may be measured. And this deformation is then averaged (after appropriate superposition after appropriate rotations), and the average can be used to determine the influence function In other embodiments, the source point of a specific part can be (e.g., a quarter of the wafer 102) measurement influence function The influence function is then extended to the entire area of ​​the wafer 102 .

[0066] In some embodiments, the linear nature of the wafer deformation can be advantageously combined with the More specifically, you can use the The ion beam 112 at the same position irradiates the wafer, which uniformly deforms along with the deposited film, and a continuous deformation increment can be measured after each ion beam irradiation. etc., each increment represents deformation independent of other doses previously received. This process can be repeated until a substantial ion dose is delivered to the film. At such a large dose (where a significant percentage of the atomic bonds in the film are broken by the ions), the wafer deformation becomes saturated, and additional doses received at the same location in the film do not result in any significant further change in wafer deformation. Once the film is saturated with ions, the film can be removed (chemically or physically), a new film can be deposited on the same wafer, and additional series of ion implantation experiments can be performed.

[0067] Reference again Figure 6 In some embodiments, instead of (or in addition to) performing a spot beam experiment 615, process 600 may include performing a spot beam simulation 625. More specifically, finite element analysis (FEA) methods may be used to simulate the pressure exerted by the ion-modified film. Deformation caused For example, the deformation can be determined by solving the classical wave equation with appropriate boundary conditions (e.g., supported boundary conditions, free boundary conditions, etc.) The simulated deformation can then be For influence function Calculate 635 , for example, as described above in conjunction with the deformation measured in the spot beam experiment 615 .

[0068] In some embodiments, process 600 may include obtaining an analytical solution for the spot beam, as shown in block 627. For example, the operations of block 627 may include transforming the influencing function into a set of suitable functions (e.g., cos mφ and sin mφ angular functions) and a set of radial polynomials (e.g., Bessel polynomials, Laguerre polynomials, Zernike polynomials, and / or the like). In some embodiments, the operation of block 627 may include obtaining the influence function Appropriate analytical representation.

[0069] The influence function obtained at block 635 Enables the computing device to perform a regression calculation 650 to determine an ion implantation map having a film-dependent (eg, material-dependent and / or thickness-dependent) coefficient K. The regression calculation 650 may include calculating the inverse influence function The inverse influence function is then convolved with the deformation of the wafer / film structure:

[0070]

[0071] In some implementations, convolution may perform a matrix multiplication:

[0072]

[0073] Its use at point The radius vector on the grid Discrete representation, each point and an element area A = Δl x ×Δl y In some embodiments, the two-dimensional deformation (Similarly, and ion implantation diagram ) is represented as a row (or column) vector whose dimension (number of components) is equal to the number of points in the grid. Since the wafer typically has a circular shape, the number of points associated with different horizontal and vertical lines of the wafer need not be the same. Similarly, the influence function and inverse influence function The inverse influence function can be calculated as the matrix that is the inverse of the influence function

[0074]

[0075] where δ jl is the Kronecker delta symbol.

[0076] In some embodiments, direct application of the regression calculation may be possible for at least some points of the wafer / film structure. The negative ion density A negative ion density means that for the corresponding point, the stress in the film must increase rather than decrease. However, ions can reduce stress in the film (e.g., by breaking the crystalline bonds of the film material), and under certain conditions, it may be more difficult to achieve increased stress. This situation can be handled using a variety of different techniques. In one embodiment, a film with a larger thickness t (which induces more strain in the wafer) can be deposited on the wafer, for example by adding more material to the film already deposited on the wafer and recalculating the ion implantation map 660 (e.g., by repeating blocks 630-650). In another embodiment, the film thickness can remain unchanged. Conversely, the target wafer deformation can be modified For example, instead of trying to achieve a perfectly flat wafer with the following equation:

[0077]

[0078] Instead, the ion implantation dose can be The cost function COST is selected to minimize an appropriate choice. In some embodiments, the cost function can be a least squares average cost function, such as:

[0079]

[0080] In some embodiments, one or more constraints may be included in the cost function. For example, some constraints may include one or more of the following: the density of implanted ions is a positive function of The density of implanted ions at any location in the film is limited to a maximum value. The condition that the maximum implanted ion density does not exceed the minimum density by a certain amount α (n MAX ≤αn MIN ); The range of change of implanted ion density is limited to a certain range (n MAX -n MIN ≤β); Constraints on the maximum film density; Constraints on the maximum absolute deformation Constraints for the maximum residual stress and / or any other constraints that the process supervisor may establish.

[0081] At block 670, the calculated ion implantation map 660 may be applied to a stress compensating film, for example, as described below in conjunction with Figure 9A-9B As disclosed.

[0082] Figure 8 Depicted are simulation results of deformations caused by an ion implantation beam directed at different locations on a wafer / film structure, according to at least one embodiment. In example 802, the ion implantation beam is directed at the center of the wafer / film structure, resulting in deformation 804; lighter (darker) areas of the wafer / film structure indicate larger (smaller) deformations. In example 806, the ion implantation beam 112 is directed at the middle portion of the wafer / film structure, resulting in deformation 808. In example 810, the ion implantation beam 112 is directed at the edge portion of the wafer / film structure, resulting in deformation 812.

[0083] Figure 9AAn ion implantation system 900 is schematically illustrated, according to at least one embodiment, that can perform ion implantation into a stress-compensating layer. The ion implantation system 900 can be part of a semiconductor manufacturing system that includes one or more processing chambers for processing wafers. The ion implantation system 900 can be or include the ion beam implanter 110 of FIG. 1 . While for purposes of illustration, the stress mitigating beam used to modify stress in the stress-compensating layer 108 is referred to as an ion beam (e.g., ion beam 112), in some embodiments, the stress mitigating beam can include particles of other species (e.g., electrons), electromagnetic waves (e.g., ultraviolet light, visible light, infrared light, etc.), and / or suitable combinations thereof. The ion implantation system 900 can include an ion source 902 for generating an ion beam 904. The ion source 902 can include a chamber (e.g., a plasma chamber) for generating ions. The ion source 902 can be powered by a power supply 906 and can include an extraction electrode assembly (not shown). The ion implantation system 900 can include a mass spectrometer 908 and a collimating and focusing column 910. The collimation and focusing column 910 can direct the ion beam 112 toward the wafer 102. The wafer 102 can be supported by a support table 912. In some embodiments, the support table 912 and wafer 102 can remain stationary while components of the ion implantation system 900 are repositioned relative to the wafer 102 while the ion beam 112 is scanned across the wafer 102. In some embodiments, the ion implantation system 900 can remain stationary while the support table 912 repositions the wafer 102. The ion beam 112 can be scanned in multiple directions, such as along the x-axis and along the y-axis according to any suitable predetermined pattern, such as back and forth along the x-axis, in a spiral pattern, etc. In various embodiments, the ion beam 112 can be scanned at a frequency of a few hertz, tens of hertz, hundreds of hertz, a few kilohertz, or higher.

[0084] The operation of the ion implantation system 900 can be controlled by a controller 914, which can include any suitable computing device, microcontroller, or any other processing device having a processor (e.g., a central processing unit (CPU), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), and / or the like) and a memory element (e.g., a random access memory (RAM), a read-only memory (ROM), flash memory, and / or the like), or any combination thereof. The controller 914 can control the operation of the power supply 906, the support table 912, and / or various other components and modules of the ion implantation system 900. The controller 914 can include an ion beam simulation module 916 that can perform simulations to determine a target intensity of the ion beam 112 to be used to mitigate various wafer deformations. In some embodiments, the support table 912 can apply a tilt to the wafer 102 (e.g., in one or two spatial directions) to change the angle of incidence of the ion beam 112 relative to the wafer 102. In some embodiments, the controller 914 can tilt the ion implantation system 900 relative to the wafer 102 rather than tilting the wafer 102.

[0085] Figure 10 Described according to at least one embodiment, can support the block diagram of the example computer system 1000 of the operation of the present disclosure.In various illustrative examples, example computer system 1000 can be or include the controller 914 of Figure 9.Example computer system 1000 can be connected with other computer systems in LAN, internal network, external network and / or the Internet.Computer system 1000 can operate as a server in a client-server network environment.Computer system 1000 can be a personal computer (PC), set-top box (STB), server, network router, switch or bridge, or any device that can execute a set of instructions (executed sequentially or otherwise) that specify the action to be taken by the device.Further, although only a single example computer system is described, the term "computer" should also be considered to include the collection of any computers that execute a set (or multiple sets) of instructions to perform any one or more methods discussed herein, either individually or collectively.

[0086] The example computer system 1000 may include a processing device 1002 (also referred to as a processor or CPU), a main memory 1004 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous dynamic random access memory (SDRAM), etc.), a static memory 1006 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory (e.g., a data storage device 1018), which may communicate with each other via a bus 1030.

[0087] The processing device 1002 represents one or more general-purpose processing devices, such as a microprocessor, a central processing unit, or the like. The processing device 1002 may include processing logic 1026. The processing device 1002 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing another instruction set, or a processor implementing a combination of instruction sets. The processing device 1002 may also be one or more special-purpose processing devices, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), a network processor, or the like. In accordance with one or more aspects of the present disclosure, the processing device 1002 may be configured to execute instructions that implement the example process 600 for performing impact function-based mitigation of wafer deformation.

[0088] The example computer system 1000 may further include a network interface device 1008, which may be communicatively coupled to a network 1020. The example computer system 1000 may further include a video display 1010 (e.g., a liquid crystal display (LCD), a touch screen, or a cathode ray tube (CRT)), an alphanumeric input device 1012 (e.g., a keyboard), a cursor control device 1014 (e.g., a mouse), and an acoustic signal generating device 1016 (e.g., a speaker).

[0089] The data storage device 1018 may include a computer-readable storage medium (or more specifically, a non-transitory computer-readable storage medium) 1024 on which is stored one or more sets of executable instructions 1022. The executable instructions 1022 may include executable instructions for performing the example process 600 for implementing the impact function-based mitigation of wafer deformation according to one or more aspects of the present disclosure.

[0090] The executable instructions 1022 may also reside, completely or at least partially, within the main memory 1004 and / or within the processing device 1002 during execution of such instructions by the example computer system 1000, the main memory 1004 and the processing device 1002 also constituting computer-readable storage media. The executable instructions 1022 may further be transmitted or received over a network via the network interface device 1008.

[0091] Although Figure 10While the computer-readable storage medium 1024 is shown as a single medium, the term "computer-readable storage medium" should also be considered to include a single medium or multiple media (e.g., a centralized or distributed database and / or associated caches and servers) that store one or more sets of operating instructions. The term "computer-readable storage medium" should also be considered to include any medium that can store or encode a set of instructions for execution by a machine, causing the machine to perform any one or more of the methods described herein. Thus, the term "computer-readable storage medium" should be considered to include (but not be limited to) solid-state memory and optical and magnetic media.

[0092] Some portions of the foregoing detailed description are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is herein, and generally, considered to be a self-consistent sequence of steps leading to a desired result. These steps are those requiring physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It proves convenient at times, primarily for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0093] It should be remembered, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, it will be understood from the following discussion that discussions throughout the description utilizing terms such as "identify," "determine," "store," "adjust," "result in," "return," "compare," "create," "stop," "load," "copy," "throwing," "replace," "execute," or similar terms refer to actions and processes of a computer system or similar electronic computing device that manipulate and transform data represented as physical (electronic) quantities within the computer system's caches and memory into other data similarly represented as physical quantities within the computer system's memory or caches or other such information storage, transmission, or display devices.

[0094] Examples of the present disclosure also relate to an apparatus for performing the methods described herein. This apparatus may be specially constructed for the desired purpose, or it may be a general-purpose computer system selectively programmed by a computer program stored in the computer system. This computer program may be stored in a computer-readable storage medium, such as, but not limited to, any type of disk (including optical disks, CD-ROMs, and magneto-optical disks), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic disk storage media, optical storage media, flash memory devices, other types of machine-accessible storage media, or any type of medium suitable for storing electronic instructions, each of which is coupled to a computer system bus.

[0095] The methods and displays presented herein are not inherently related to any particular computer or other device. Various general-purpose systems may be used with the programs taught herein, or it may prove convenient to construct a more specialized device to perform the required method steps. The structures required for various such systems will appear in the following description. Furthermore, the scope of this disclosure is not limited to any particular programming language. It will be understood that various programming languages ​​may be used to implement the teachings of this disclosure.

[0096] It is to be understood that the above description is intended to be illustrative and not restrictive. Many other examples of implementations will be apparent to those skilled in the art upon reading and understanding the above description. Although this disclosure describes specific examples, it will be appreciated that the systems and methods of the present disclosure are not limited to the examples described herein, but may be practiced with modification within the scope of the appended claims. Accordingly, the specification and drawings should be viewed in an illustrative and not a restrictive sense. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A method for correcting out-of-plane deformation (OPD) of a substrate, the method comprising: depositing a stress-compensating layer (SCL) on the substrate; obtaining a profile of the OPD of the substrate using optical inspection data; obtaining, by a processing device, a data set comprising a representation of an influence function for the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact; performing a regression calculation to determine a distribution of stress mitigating irradiation for mitigating the SCL of the OPD of the substrate based at least on the profile of the OPD of the substrate and the influence function; as well as Stress mitigation irradiation of the SCL is performed using the determined profile of the stress mitigation irradiation.

2. The method of claim 1, wherein the influence function is determined based on one or more simulations characterizing the OPD of a reference substrate caused by a known mechanical influence. The method of claim 2 , wherein the one or more simulations employ finite element analysis.

4. The method of claim 1 , wherein the influence function is determined using one or more experiments, wherein each of the one or more experiments comprises measuring an OPD of a reference substrate induced by a reference stress mitigating beam directed into a reference SCL, the reference SCL being deposited on the reference substrate. The method of claim 1 , wherein the regression calculation is subject to one or more constraints.

6. The method of claim 1, wherein the profile of the stress relief irradiation of the SCL is determined to minimize an average squared OPD of substrate deformation after the stress relief irradiation of the SCL.

7. The method of claim 1, wherein the substrate comprises a front side and a back side, wherein the front side comprises one or more fabricated features, and wherein the SCL is deposited on the back side of the substrate.

8. The method of claim 1 , wherein depositing the SCL on the substrate comprises: identifying a profile of the OPD of the substrate using optical inspection data; performing a polynomial decomposition on the identified profile to determine a plurality of polynomial coefficients, each of the plurality of polynomial coefficients characterizing a corresponding one of a plurality of elemental deformed shapes of the substrate; as well as identifying one or more characteristics of a stress compensating layer (SCL) for the substrate based on at least a subset of the plurality of polynomial coefficients, wherein the one or more characteristics of the SCL include at least one of: the material of the SCL; or The thickness of the SCL.

9. The method of claim 1, further comprising: determining settings for the stress mitigation irradiation of the SCL, wherein the settings include one or more of: a particle type of a stress mitigation beam used for the stress mitigation irradiation of the SCL; the energy of the particles of the stress mitigation beam; or An angle of incidence of the particles of the stress mitigation beam on the SCL.

10. A system comprising: Memory; as well as a processing device, the processing device being communicatively coupled to the memory, the processing device being configured to: depositing a stress-compensating layer (SCL) on a substrate; obtaining a profile of out-of-plane deformation (OPD) of the substrate using optical inspection data; obtaining, by a processing device, a data set comprising a representation of an influence function on the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact; performing a regression calculation to determine a profile of stress mitigating irradiation that mitigates the SCL of the OPD of the substrate based at least on the profile of the OPD of the substrate and the influence function; as well as Stress mitigation irradiation of the SCL is performed using the determined profile of the stress mitigation irradiation.

11. The system of claim 10, wherein the influence function is determined based on one or more simulations characterizing the OPD of a reference substrate induced by a known mechanical influence.

12. The system of claim 11, wherein the one or more simulations employ finite element analysis.

13. The system of claim 10, wherein the influence function is determined using one or more experiments, wherein each of the one or more experiments comprises measuring an OPD of a reference substrate induced by a reference stress mitigation beam directed into a reference SCL deposited on the reference substrate.

14. The system of claim 10, wherein the regression calculation is subject to one or more constraints.

15. The system of claim 10, wherein the profile of the stress mitigation irradiation of the SCL is determined to minimize an average squared OPD of substrate deformation after the stress mitigation irradiation of the SCL.

16. The system of claim 10, wherein the substrate comprises a front side and a back side, wherein the front side comprises one or more fabricated features, and wherein the SCL is deposited on the back side of the substrate.

17. The system of claim 10, wherein to deposit the SCL on the substrate, the processing equipment is configured to: identifying a profile of the OPD of the substrate using optical inspection data; performing a polynomial decomposition on the identified profile to determine a plurality of polynomial coefficients, each of the plurality of polynomial coefficients characterizing a respective one of a plurality of elemental deformed shapes of the substrate; and identifying one or more characteristics of a stress compensating layer (SCL) for the substrate based on at least a subset of the plurality of polynomial coefficients, wherein the one or more characteristics of the SCL include at least one of: the material of the SCL; or The thickness of the SCL.

18. The system of claim 10, wherein the processing device is further configured to: determining settings for the stress mitigation irradiation of the SCL, wherein the settings include one or more of: a particle type of a stress mitigation beam used for the stress mitigation irradiation of the SCL; the energy of the particles of the stress mitigation beam; or An angle of incidence of the particles of the stress mitigation beam on the SCL.

19. A semiconductor manufacturing system, comprising: one or more processing chambers for processing a substrate; as well as A computing device configured to: depositing a stress-compensating layer (SCL) on a substrate; obtaining a profile of out-of-plane deformation (OPD) of the substrate using optical inspection data; obtaining a data set comprising a representation of an influence function on the substrate, wherein the influence function characterizes a deformation response of the substrate caused by a point-like mechanical impact; performing a regression calculation to determine a profile of stress mitigating irradiation that mitigates the SCL of the OPD of the substrate based at least on the profile of the OPD of the substrate and the influence function; as well as Stress mitigation irradiation of the SCL is performed using the determined profile of the stress mitigation irradiation.

20. The semiconductor manufacturing system of claim 19, wherein the influence function is determined based on at least one of the following: One or more simulations characterizing the OPD of a reference substrate induced by a known mechanical influence; or One or more experiments, wherein each of the one or more experiments comprises measuring an OPD of a reference substrate induced by a reference stress mitigating beam directed into a reference SCL deposited on the reference substrate.

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