PCB processing

Abstract

The present invention relates to a method for processing a substrate, the method comprising: a) providing the substrate on a support; b) measuring the properties of the substrate and / or rinse solution; c) controlling the addition of one or more additives to the rinse solution based on the measurements to adjust the pH and / or conductivity of the rinse solution to predetermined values; and d) providing the rinse solution to a first surface of the substrate through one or more nozzles. The present invention also relates to a method for manufacturing a system and a device for processing a substrate.

Description

Technical Field

[0001] Cross-references to related applications

[0001] This application claims the priority of European and US Application No. 23169184.1 filed on April 21, 2023, and incorporates the whole of it by reference into this application.

[0002]

[0002] The present invention relates to a method for processing a substrate before exposing the substrate to radiation in a lithographic apparatus. The present invention also relates to a system for processing a substrate and a method for manufacturing a device.

Background Art

[0003]

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of devices (e.g., integrated circuits (ICs)). A lithographic apparatus can project a pattern from a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004]

[0004] A substrate within a lithographic apparatus is typically supported by a support mechanism / substrate holder. When the substrate is a silicon wafer (e.g., during the manufacture of an integrated circuit), the support mechanism / substrate holder is typically referred to as a wafer table.

[0005]

[0005] The wavelength of the radiation used by a lithographic apparatus to project a pattern onto a substrate determines the minimum size of the features that can be formed on this substrate. Using a lithographic apparatus that uses EUV radiation, which is electromagnetic radiation having a wavelength within the range of 4 to 20 nm, smaller features can be formed on a substrate than using a lithographic apparatus that uses deep ultraviolet (DUV) (e.g., having a wavelength of 193 nm).

[0006]

[0006] As the size of features formed in the lithography process decreases, the performance requirements for all aspects of the lithography equipment and materials become more stringent.

[0007]

[0007] The substrate holder used during the manufacturing of the device typically includes a crowbar to reduce the impact of particle contamination on the back surface of the substrate.

[0008]

[0008] A typical semiconductor substrate has SiO2 on the back surface of the substrate (for example, the back surface of the wafer). x or Si x N y It has a thin silicon layer, which can lead to the formation of Si-OH groups on its surface. As a result, it becomes the back surface of the substrate with a high surface energy. Charges (i.e., protons and electrons) can move across the back surface of such a substrate.

[0009]

[0009] Before loading the substrate into the lithography apparatus, the back surface of the substrate is rinsed to remove contaminants. For example, an H2O rinse may be used, which involves scrubbing the central portion of the substrate. The substrate may then be spin-dried. This rinsing step extends the cleaning interval of the substrate holder and improves the effective throughput of the lithography apparatus.

[0010]

[0010] During the spin coating process, the insulating substrate (i.e., the substrate containing the dielectric material) becomes charged when the rinse solution is supplied and further when the substrate dries due to the flow potential. The amount of charge depends on various factors, including the amount of rinse solution used, the length of time the rinse solution is supplied, the spin speed, the conductivity of the rinse solution, and the pH relative to the isoelectric point of the substrate. Due to the high surface energy of the back surface of the substrate, water may adhere to the surface, and an adsorbed monolayer of H2O may remain on the back surface of the substrate even after spin drying. When the substrate is loaded into the substrate holder, residual water may be present between the back surface of the substrate and the bar of the substrate holder.

[0011]

[0011] Due to previous processing steps, charges may be present on the substrate. For example, previous processing steps may result in charges being trapped between two insulating layers of the substrate. This is shown in Figure 4. Specifically, Figure 4 shows a) fixed charges 42 (generated by processes performed before the final (insulating) layer 41 is deposited, and trapping charges 42), b) charges on the outside of the substrate 43 (which can be removed by contact with water, for example), c) trapped charges that are also present on the wafer surface (charges 44 with the same sign), and d) trapped charges that are also present on the wafer surface (charges 45 with the opposite sign).

[0012]

[0012] Electrochemical corrosion of the bar material in the substrate holder may occur, and the height of certain bars may change over time. This can lead to an increase in the wafer load grid (WLG), a decrease in non-uniform flatness, and localized angular focus problems due to the inability to properly focus the image on the substrate. As a result, the substrate holder may no longer meet the stringent performance requirements of the lithography equipment and may need to be replaced.

[0013]

[0013] One way to reduce the reactivity of bar is to prevent oxidation by applying a cathode overpotential to the bar. However, as taught by Mitraka et al. in J.Mater.Chem.A,2017,5:4404-4412, applying a cathode overpotential to bar in the presence of air can lead to the formation of reactive oxygen species that can corrode the bar.

[0014]

[0014] Another method to reduce bar reactivity is to apply an anode overpotential to create a passivation layer, sealing the surface of the underlying layer and preventing further oxidation. However, the passivation layer can only be applied to certain metal substrates in which the corresponding metal oxide can form a closed oxide layer, preventing further corrosion of the underlying metal layer. In many metals, the metal oxide does not form a closed layer, and further corrosion of the underlying metal surface may occur. For carbon-based materials such as DLC or diamond, corrosion of the carbon-based layer can cause the oxide to dissolve in the solution or, possibly, in gas species such as CO2, H2O, or CO.

[0015]

[0015] To prevent charge diffusion across the back surface of the wafer, hydrophobic wafer back coatings such as hexamethyldisilazane (HMDS), polytetrafluoroethylene (PTFE), and cyclic azasilane have been used (see, for example, WO2021122065A1). Such coatings are monolayers with hydrophobic end groups that often self-assemble. This method reduces the effects of corrosion and mitigates oxidation of DLC coatings because charge movement on the back surface of the wafer is prevented. However, this method adds an additional process step, increasing complexity and cost. The coating must be added before inserting the wafer into the lithography system and removed after lithography. Furthermore, this method only reduces charge mobility; it does not reduce or remove the charge.

[0016]

[0016] In EUV applications, the effect of charge is mediated through the adhesive force between conductive bales that generate Miller charges when the back surfaces of charged substrates come into contact. The additional Coulomb attraction is secondarily increased, and therefore the benefits of reducing charge density and peak charge levels by homogenization are also secondarily increased (see Figure 3).

[0017]

[0017] In the case of EUV, the back surface coating of the wafer does not help to reduce WLG because it prevents the diffusion of charge to the conductive bar. This increases the adhesive Coulomb force between the bar and the charged back surface of the wafer.

[0018]

[0018] A further method used to mitigate the effect of charge on the back surface of the substrate is to incorporate carbon dioxide into the rinse water before rinsing the back surface of the wafer (see, for example, US2005133066A1). This results in a solution with a pH of approximately 4.1 and a conductivity of approximately 0.02 mS / cm. Rinsing with this solution slightly reduces the charge on the back surface of the substrate and can disperse the charge profile of the pre-charged back surface of the substrate. However, this depends on the specific substrate material. Furthermore, rinsing with a CO2 solution has only a limited effect in resolving WLG drift and flatness degradation. Supersaturated CO2 solutions change in concentration rapidly when exposed to air. As a result, variations in the CO2 concentration and pH of the rinse water during the rinsing process increase, leading to greater variations when trying to remove charge from the substrate. Furthermore, when rinsing at high spin speeds, the conductivity of aqueous CO2 is insufficient, leading to the continued existence of charged regions when the spin speed exceeds 2000 rpm. [Overview of the project]

[0019]

[0019] Considering the above, there is still a need to develop improved methods and systems to mitigate the effects of electric charge on the substrate.

[0020]

[0020] The present invention relates in particular to a method for processing a substrate, the method comprising: a) providing the substrate on a support; b) measuring the properties of the substrate and / or rinse solution; c) adjusting the pH value and / or conductivity of the rinse solution to a predetermined value by controlling the addition of one or more additives to the rinse solution based on the measurement; and d) providing the rinse solution to a first surface of the substrate via a nozzle.

[0021]

[0021] The present invention also relates to a system for processing a substrate, the system comprising: a) a support for supporting the substrate; b) a nozzle arranged to provide a rinse liquid to a first surface of the substrate; c) a measurement system configured to measure a characteristic of the substrate and / or the rinse liquid; and d) a controller configured to adjust the pH value and / or conductivity of the rinse liquid based on a measurement by the measurement system by controlling the addition of one or more additives to the rinse liquid.

[0022]

[0022] The present invention also relates to a method of manufacturing a device including a method for processing a substrate discussed herein.

[0023]

[0023] Such a method and system enable controlling the charge on a substrate, for example on the back surface of the substrate, before inserting the wafer into a lithography apparatus. This has several advantages including minimizing the corrosion rate of the substrate holder and thus reducing the frequency with which the substrate holder needs to be replaced. This reduces the frequency with which maintenance needs to be performed and the frequency with which the substrate holder / wafer table needs to be replaced, improving the throughput of the lithography apparatus and the efficiency of device production.

Brief Description of the Drawings

[0024]

[0024] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0025]

[0025] [Figure 1] Figure 1 is a schematic view of a lithography system including a lithography apparatus and a radiation source.

[0026] [Figure 2] Figure 2 shows a schematic view of a lithographic cell.

[0027] [Figure 3] Figure 3 shows the effect of charge on a wafer load grid (WLG) on a substrate holder.

[0028] [Figure 4]Figures 4a, 4b, 4c, and 4d illustrate various methods by which electric charge can accumulate on a substrate.

[0029] [Figure 5] Figure 5a shows the effect of rinsing the back surface of a thermal SiO2 wafer with CH3COOH / H2O, H2O, and CO2 / H2O on the charge. Figure 5b is the same graph as Figure 5a, but shows a portion of the graph with a different y-axis scale.

[0030] [Figure 6] Figure 6 shows the effect of rinsing the back surface of an LPCVD Si3N4 wafer with CH3COOH / H2O and H2O on the charge.

[0031] [Figure 7] Figure 7 shows the effects of rinsing a pre-charged SiO2 wafer with water at 2000 rpm and then with acetic acid at 2400 rpm.

[0032] [Figure 8] Figure 8 shows the surface potential of a 150 nm thermal SiO2 layer coated on the back surface of a wafer with charge patterns applied by desalted water spin rinsing, before and after treatment with CH3COOH solution.

[0033] Figure 9 shows a system according to the present invention that acquires a spatial profile based on the measurement of the charge of a substrate.

[0034] Figure 10 shows a system according to the present invention that acquires a spatial profile based on substrate charge measurement and performs FTIR (Fourier Transform Infrared) spectroscopy.

[0026]

[0035] The schematic diagram and view illustrate the components described below. However, the components shown in the diagram are not to scale. [Modes for carrying out the invention]

[0027]

[0036] Hereafter, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. The following description will refer to the accompanying drawings, and unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described below in the description of exemplary embodiments do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with aspects related to the present invention as described in the accompanying claims.

[0028]

[0037] Figure 1 schematically shows a lithography apparatus LA. The lithography apparatus includes an illumination system (also called an illuminator) IL configured to adjust a radiation beam B (e.g., EUV radiation or DUV radiation), a mask support (e.g., a mask table) MT connected to a first positioner PM built to support a patterning device (e.g., a mask) MA and configured to precisely position the patterning device MA according to specific parameters, a substrate support (e.g., a substrate table) WT connected to a second positioner PW built to hold a substrate (e.g., a resist-coated wafer) W and configured to precisely position the substrate support WT according to specific parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., including one or more dies).

[0029]

[0038] During operation, the illumination system IL receives the radiated beam B from the radiation source SO, for example, via the beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, to guide, shape, and / or control the radiation. The illuminator IL may be used to adjust the radiated beam B so that it has a desired spatial and angular intensity distribution in its cross-section, in the face of the patterning device MA.

[0030]

[0039] As used herein, the term “projection system” PS should be broadly interpreted to encompass all types of projection systems, including refractive, reflective, reflective-refracting, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, that are appropriate for the exposure radiation used and / or other factors such as the use of immersion liquid or vacuum. As used herein, the term “projection lens” should be considered synonymous with the more general term “projection system” PS.

[0031]

[0040] The lithography apparatus may be of a type in which at least a portion of the substrate W is covered with an immersion liquid such as water having a relatively high refractive index to fill the space between the projection system PS and the substrate W (also known as immersion lithography). Further information relating to immersion technology is provided in US Patent No. 6952253, which is incorporated herein by reference.

[0032]

[0041] The lithography apparatus may be of a type having two or more substrate support WTs (also called a "dual-stage" apparatus). In such a "multi-stage" machine, the substrate support WTs can be used in parallel, and / or, while the preparation steps for subsequent exposure of the substrate W are being performed on the substrate W located on one substrate support WT, the other substrate W may be used to expose a pattern on the other substrate W.

[0033]

[0042] In addition to the substrate support WT, the lithography apparatus may include a measurement stage (not shown in Figure 1). The measurement stage is positioned to hold sensors and / or a cleaning device. The sensors may be positioned to measure the characteristics of the projection system PS or the characteristics of the radiating beam B. The measurement stage may hold multiple sensors. The cleaning device may be positioned to clean a part of the lithography apparatus, such as a part of the projection system PS or a part of the system that provides the immersion fluid. The measurement stage may move under the projection system PS when the substrate support WT is away from the projection system PS.

[0034]

[0043] During operation, the radiated beam B is incident on a patterning device (e.g., mask MA) held on a mask support MT, and a pattern is formed by the pattern (design layout) present on the patterning device MA. After passing through the mask MA, the radiated beam B passes through a projection system PS, which focuses the beam onto a target portion C on the substrate W. Using a second positioner PW and a position measuring system PMS, the substrate support WT can be precisely moved to position, for example, various target portions C in a focused and aligned position within the path of the radiated beam B. Similarly, using a first positioner PM and optionally another position sensor (not explicitly shown in Figure 1a), the patterning device MA can be precisely positioned relative to the path of the radiated beam B. The patterning device MA and the substrate W may be aligned using mask alignment marks M1 and M2 and substrate alignment marks P1 and P2. In the example, the substrate alignment marks P1 and P2 occupy dedicated target areas, but the substrate alignment marks can also be placed in the space between target areas. When the substrate alignment marks P1 and P2 are positioned between target areas C, they are known as scribe line alignment marks.

[0035]

[0044] In lithography equipment, the top surface of the substrate or wafer to be exposed must be positioned with great precision within the optimal focal plane of the spatial image of the pattern projected by the projection system. To achieve this, the substrate or wafer can be held on a substrate holder or wafer table. Multiple burrs can be provided on the surface of the substrate holder that supports the substrate, and the distal ends of the burrs can lie coplanar within the nominal support surface. Although there are many burrs, their total distal cross-sectional area is a few percent of the substrate's surface area, e.g., less than 5%, because the cross-sectional area parallel to the support surface is small. By reducing the gas pressure in the space between the substrate holder and the substrate relative to the pressure on the substrate, a clamping force can be generated to hold the substrate in place.

[0036]

[0045] As shown in Figure 2, the lithography apparatus LA may form part of a lithography cell LC (sometimes called a lithocell or (litho)cluster), which often includes equipment for performing pre-exposure and post-exposure processes on the substrate W. Conventionally, such equipment includes a spin coater SC for depositing the resist layer, a developer DE for developing the exposed resist, a cooling plate CH and a bake plate BK (for example, to adjust the temperature of the substrate W, for example, to adjust the solvent in the resist layer). A substrate handler or robot RO picks up the substrate W from input / output ports I / O1 and I / O2, moves the substrate W between various process equipment, and delivers the substrate W to the loading bay LB of the lithography apparatus LA. The devices within the lithocell are often collectively called tracks and are typically under the control of a track control unit TCU, which may be controlled by a monitoring and control system SCS, which may also control the lithography apparatus LA (for example, via a lithography control unit LACU).

[0037]

[0046] The wafers discussed herein are examples of substrates that can be supported by a substrate holder. When the substrate is referred to as a wafer, the substrate holder is usually called a wafer table.

[0038]

[0047] Contact between the back surface of the substrate and the burl material in the presence of water can lead to electrochemical corrosion of the burl material (e.g., diamond-like carbon (DLC) coating on the burl). Over time, the height of certain burl surfaces may change, leading to a non-uniform decrease in flatness and potentially causing localized angular focus problems, as the image may no longer be able to properly focus on the substrate. As a result, the substrate holder may no longer meet the stringent performance requirements of the lithography equipment and may need to be replaced. Therefore, minimizing the rate of burl corrosion is key to maximizing the lifespan of the substrate holder and the efficiency of device production.

[0039]

[0048] In addition to the above, during loading, the substrate may come into contact with specific points on the substrate holder, resulting in displacement errors in the x and y directions. These errors can be exacerbated if the back surface of the substrate is charged. These errors have been observed to drift over time and are reflected in the wafer load grid (WLG) drift.

[0040]

[0049] Excluding the wet substrate rinsing step prevents any measurable decrease in flatness even after passing 1000 substrates through an accelerated test environment. However, completely eliminating the wet substrate cleaning step is not possible due to the increased frequency of substrate holder cleaning and the resulting decrease in lithography apparatus throughput. Therefore, reducing the amount of moisture and / or surface charge present on the back surface of the substrate after cleaning is key to minimizing the decrease in flatness.

[0041]

[0050] Wafer load grid (WLG) is also a serious problem for lithography. Localized damage to the substrate holder in the x, y, and / or z directions negatively impacts overlays (i.e., positional errors of features in one layer of the patterned substrate relative to features in another layer, which can arise from errors in the positioning of the substrate relative to the spatial image during exposure) at the nanometer level. Over time, the WLG drifts to higher values, resulting in overlay problems and potentially reducing the lifespan of the substrate holder. Minimizing the rate of burl corrosion is also key to minimizing the rate of WLG drift.

[0042]

[0051] The lifetime loss (WLG) of electrostatic clamps (ESCs) used in extreme ultraviolet (EUV) lithography is also a problem, limiting the effective lifespan of ESCs in mass device production using EUV lithography. Minimizing the rate of burl corrosion is also important in minimizing ESC WLG.

[0043]

[0052] This invention stems from the remarkable discovery that the charge on a substrate can be controlled by changing the rinsing solution provided to the substrate as part of a cleaning step before inserting the substrate into a lithography apparatus. For example, depending on a number of factors including (i) the presence of existing charge on the substrate before the rinsing step, (ii) the isoelectric point (IEP) of the substrate when in contact with water, (iii) the pH value of the rinsing solution, and (iv) the conductivity of the rinsing solution, it is possible to reduce or maintain the charge on the wafer. Controlling the charge on the substrate before inserting the substrate into a lithography apparatus offers numerous advantages. For example, reducing the charge on the substrate reduces the flatness of the substrate holder and / or the speed of the wafer load grid (WLG), and also reduces the rate of electrochemical corrosion of the bar in the lithography apparatus, etc.

[0044]

[0053] The present invention particularly provides a method for processing a substrate, the method comprising: a) providing the substrate on a support; b) measuring the properties of the substrate and / or a rinse solution; c) adjusting the pH and / or conductivity of the rinse solution to a predetermined value by controlling the addition of one or more additives to the rinse solution based on the measurements; and d) providing the rinse solution to a first surface of the substrate via a nozzle (or similar).

[0045]

[0054] The characteristics to be measured may be at least one of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The characteristics to be measured may be at least two of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The characteristics to be measured may be at least three of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The characteristics to be measured may be all of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. For example, the characteristic to be measured may be the charge on the substrate. Alternatively, the characteristic to be measured may be the isoelectric point (IEP) of the first surface of the substrate when in contact with water. Alternatively, the characteristic to be measured may be the pH value of the rinse solution. Alternatively, the characteristic to be measured may be the conductivity of the rinse solution. The characteristic to be measured may be both the charge on the substrate and the isoelectric point (IEP) of the first surface of the substrate when in contact with water. The characteristic to be measured may be both the charge on the substrate and the pH value of the rinse solution. The characteristic to be measured may be both the isoelectric point (IEP) of the first surface of the substrate when in contact with water and the pH value of the rinse solution. The characteristic to be measured may be both the charge on the substrate and the conductivity of the rinse solution. The characteristic to be measured may be both the pH value of the rinse solution and the conductivity of the rinse solution. The characteristic to be measured may be both the isoelectric point (IEP) of the first surface of the substrate when in contact with water and the conductivity of the rinse solution.

[0046]

[0055] The rinsing solution is provided to the first surface of the substrate via a nozzle. Therefore, in the method of the present invention, the first surface of the substrate can be cleaned with the rinsing solution. The rinsing solution can be provided to the back or front surface of the substrate. Preferably, the rinsing solution is provided to the back surface of the substrate. Therefore, in the method of the present invention, the back surface of the substrate can be cleaned with the rinsing solution. In the context of the present invention, "back surface of the substrate" refers to the surface of the substrate opposite to the surface of the substrate containing the photoresist. In other words, the back surface of the substrate is the surface of the substrate opposite to the surface of the substrate that is exposed by radiation in a lithography apparatus after cleaning. In the context of the present invention, "front surface of the substrate" refers to the surface of the substrate that is exposed by radiation in a lithography apparatus.

[0047]

[0056] The characteristics to be measured may be measured on the back surface of the substrate. Therefore, the charge can be measured at one or more points (or locations) on the back surface of the substrate. If the IEP of the first surface of the substrate is measured when it comes into contact with water, the first surface may be the back surface of the substrate.

[0048]

[0057] If the characteristic being measured is the charge on the substrate, a spatial profile based on the substrate's charge measurement can be measured. Therefore, a mapping of (local) charge on the substrate, i.e., a charge map, can be obtained. Alternatively, one or more point charges can be measured at one or more points on the substrate's surface.

[0049]

[0058] The properties to be measured may be measured by any suitable apparatus. For example, an FTIR (Fourier Transform Infrared) spectrometer can be used to determine the composition of the substrate and then to estimate or calculate the IEP of the first surface of the substrate when it comes into contact with water. For example, measuring the IEP of the first surface may involve using FTIR to identify the composition of the first surface and then determining the IEP using a known value of that composition. A pH sensor or probe can be used to calculate the pH of the rinse solution. Electrical charge can be measured by any suitable apparatus, for example, an electrostatic voltmeter can be used. Conductivity can be measured by any suitable apparatus, for example, an electrical conductivity meter.

[0050]

[0059] The isoelectric point (IEP) of the first surface of the substrate (e.g., the back surface of the substrate) can be determined based on information from a previous step in the manufacturing process. The IEP may, alternatively or additionally, be determined based on in-situ or in-track FTIR measurements. The light transmittance of a particular wafer depends on its material properties. For example, the light transmittance of SiO2 differs from that of Si, resulting in different FTIR measurements. This information may be used, along with information from any previous manufacturing step, to determine or estimate the IEP of the wafer surface, for example, using known IEP values ​​related to the composition of the wafer surface. This information may also be used to determine the properties of one or more additives added to the rinse solution to adjust its pH value to a predetermined value. For example, the specific one or more compounds used as additives, their concentrations, pH, and the amount of additive added to the rinse solution can all be determined.

[0051]

[0060] If the characteristic to be measured is a characteristic of the substrate, that characteristic can be measured at any point on the wafer track. Alternatively, the characteristic of the substrate may be measured while the substrate is moving between devices. For example, the characteristic of the substrate may be measured while the substrate is inside a front-opening unified pod (FOUP).

[0052]

[0061] The present invention makes it possible to control the charge on a substrate by changing the rinse solution provided to the substrate. In particular, the properties of the rinse solution can be controlled by adding one or more additives to the rinse solution based on measurements from a measurement system. For example, the addition of one or more additives can lower the pH of the rinse solution and / or increase the conductivity of the rinse solution.

[0053]

[0062] The present invention also makes it possible to control the charge on a substrate locally, i.e., in a specific region of the substrate, as needed. For example, the method of the present invention can be performed multiple times on a single wafer, and each time it can focus on a different specific location on the wafer surface. Therefore, by using the method of the present invention, it is possible to control the local charge in a specific local region of the wafer.

[0054]

[0063] A given substrate material has a set isoelectric point (IEP) when in contact with water. When the pH of the water matches the IEP, the zeta potential is 0, and there is no net charge flow when the water is in contact with the surface of the substrate. Therefore, a rinse solution with this pH value can flow over the substrate without net charge transfer. If the pH of the water is higher than the IEP of the substrate surface, the zeta potential becomes negative, and the substrate becomes negatively charged as the water flows over it. Therefore, a rinse solution with a high pH can be used to add a negative charge to the substrate or remove a positive charge from it. Conversely, if the pH of the water is lower than the IEP of the substrate surface, the zeta potential is positive, and the substrate becomes positively charged as the water flows over it. Therefore, a rinse solution with a low pH can be used to add a positive charge to the substrate or remove a negative charge from it.

[0055]

[0064] Therefore, the composition of the outer surface of the insulating dielectric layer (e.g., SiOx, SiN) determines its interaction with the rinse solution. The pH of the rinse solution can be adjusted based on the surface composition to regulate the charge.

[0056]

[0065] Figure 8.6 on page 98 of Thomas Luxbacher's "The Zeta Potential for Solid Surface Analysis" (2014) illustrates the effect on the isoelectric point (IEP) when SiN is properly cleaned without treatment to obtain SiN with a higher IEP. Specifically, this figure shows zeta potential measurements using 1 mM KCl to determine the isoelectric point (IEP) of various typical substrate backing materials (SiO2 and SiN) in contact with water of different acidity (pH). The isoelectric point (IEP) is defined as the pH at which equilibrium is maintained between positive and negative charges on the surface. When the pH of the rinse solution is above the IEP (i.e., to the right), the substrate becomes negatively charged. When the pH of the rinse solution is below the IEP (i.e., to the left), the substrate becomes positively charged.

[0057]

[0066] The conductivity of the rinsing solution also has a significant impact. The higher the conductivity of the rinsing solution, the easier it is to transfer charge to or from the substrate during rinsing. Typically, the rinsing solution used to rinse the substrate has a conductivity of 0.1 mS / cm or higher, about 0.2 mS / cm or higher, about 0.3 mS / cm or higher, or about 0.4 mS / cm or higher, preferably about 0.5 mS / cm or higher.

[0058]

[0067] Therefore, it will be understood that when cleaning a substrate with a rinse solution, the addition of one or more additives to the rinse solution can be adjusted to impart, remove, or maintain an electric charge on the substrate.

[0059]

[0068] By providing a rinsing solution to the surface of a substrate, the charge on the substrate can be reduced. For example, if the charge on the substrate before rinsing is negative, the pH of the rinsing solution can be adjusted to a pH lower than the isoelectric point of the substrate. Rinsing can reduce the net charge on the substrate. Alternatively, if the charge on the substrate before rinsing is positive, the pH of the rinsing solution can be adjusted to a pH higher than the isoelectric point of the substrate. Rinsing can reduce the net charge on the substrate.

[0060]

[0069] By providing a rinsing solution to the surface of a substrate, the charge on the substrate can be increased. For example, if the charge on the substrate is negative before rinsing, the pH of the rinsing solution can be adjusted to a pH higher than the isoelectric point of the substrate. Rinsing increases the net charge on the substrate. Alternatively, if the charge on the substrate is positive before rinsing, the pH of the rinsing solution can be adjusted to a pH lower than the isoelectric point of the substrate. Rinsing increases the net charge on the substrate.

[0061]

[0070] By providing a rinsing solution to the surface of a substrate, the charge on the substrate may not change substantially. In this case, the pH of the rinsing solution can be adjusted to substantially match the isoelectric point of the substrate. After rinsing, the net charge on the substrate does not change. Therefore, a substrate that was not originally charged may remain uncharged after rinsing. Alternatively, if the intention is to retain a certain charge on the substrate, the pH of the rinsing solution can be adjusted to match the IEP of the substrate surface, and no net charge transfer occurs when the substrate is rinsed with the rinsing solution.

[0062]

[0071] Rinse solution is usually an aqueous solution.

[0063]

[0072] One or more additives may be in any suitable form. One or more additives are usually aqueous solutions. Alternatively, one or more additives may be solids that dissolve when added to the rinse solution. Typically, one or more additives include one or more organic acids. In the context of this invention, "organic acid" means a weakly acidic organic compound that does not completely dissociate in aqueous solution. One or more organic acids typically contain 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms. One or more organic acids may include at least one compound containing at least one group selected from carboxyl, sulfo, thiol, alcohol, enol, and phenol groups. One or more organic acids preferably contain at least one compound containing a carboxyl group. One or more organic acids may include at least one compound selected from amino acids, acids having unsaturated groups (e.g., acids containing double or triple bonds), or fluorinated organic acids.

[0064]

[0073] If the additive contains one or more organic acids, the organic acids are not particularly limited. For example, one or more organic acids include formic acid, acetic acid, glycolic acid, glyoxylic acid, oxalic acid, propionic acid, acrylic acid, propiolic acid, lactic acid, 3-hydroxypropionic acid, glyceric acid, pyruvic acid, 3-oxopropanoic acid, 2,3-dioxopropanoic acid, malonic acid, tartonic acid, 2,2-dihydroxypropanediic acid, mesooxalic acid, glycidic acid, butyric acid, isobutyric acid, crotonic acid, isocrotonic acid, methacrylic acid, vinylacetic acid, tetrolic acid, It may contain at least one of the following: acetoacetic acid, succinic acid, fumaric acid, maleic acid, malic acid, tartaric acid, oxaloacetic acid, valeric acid, caproic acid, citric acid, aconitic acid, isocitric acid, sorbic acid, enanthic acid, pimelic acid, benzoic acid, salicylic acid, caprylic acid, phthalic acid, softalic acid, terephthalic acid, pelargonic acid, trimesic acid, cinnamic acid, capric acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, trifluoroacetic acid, and uric acid.

[0065]

[0074] Preferably, one or more organic acids have a boiling point of about 80 to about 150°C at a pressure of 1 atmosphere. Organic acids with a boiling point similar to that of water are advantageous because their evaporation rate is similar to that of water. Therefore, it is easy to remove excess rinsing solution (containing water and any organic acids) after rinsing the substrate, and little to no residue of one or more additives remains on the substrate after the rinsing step. For example, spin drying may be used to remove excess water and organic acids. Furthermore, since water and organic acids evaporate at approximately the same rate, the concentration of organic acids in water remains relatively stable. The one or more organic acids may have a boiling point of about 85 to about 145°C, about 90 to about 140°C, about 95 to about 135°C, or about 100 to about 130°C at a pressure of 1 atmosphere.

[0066]

[0075] To minimize the impact of residues, additives containing only C, O, and H atoms are preferred.

[0067]

[0076] If the additive contains one or more organic acids, these one or more organic acids may include at least one of formic acid, acetic acid, or propionic acid. Preferably, the one or more organic acids include acetic acid (CH3COOH).

[0068]

[0077] The additive may contain two or more organic acids. Therefore, by using multiple organic acids as additives, the properties of the rinse solution can be changed to a specific pH value and / or conductivity. For example, the additive may contain acetic acid and citric acid.

[0069]

[0078] One or more additives may also include one or more additional compounds that impart useful properties to the rinse solution and / or improve the processing of the substrate. For example, one or more additional compounds may include one or more of soaps, inhibitors, antioxidants, and radical scavengers.

[0070]

[0079] Controlling the addition of one or more additives adjusts the pH and / or conductivity of the rinse solution to a predetermined value. The value is predetermined based on factors including 1) the specific substrate used and the isoelectric point of its surface, 2) whether it is intended to remove, add, or retain existing charges on the substrate, and 3) the sign and location of any existing charges on the substrate.

[0071]

[0080] As explained above, if the pH of water is higher than the IEP on the substrate surface, the substrate becomes negatively charged when water flows over it. Conversely, if the pH of water is lower than the IEP on the substrate surface, the substrate becomes positively charged when water flows over it. For example, the predetermined pH value may be approximately 1 to 4.5, approximately 2 to 3.5, or approximately 2.5 to 3. Alternatively, the predetermined pH value may be approximately 1.5 to 2.5, approximately 2.5 to 3.5, or approximately 3.5 to 4.5. Alternatively, the predetermined pH value may be approximately 1 to 3, approximately 1 to 2, or approximately 1 to 1.75.

[0072]

[0081] By controlling the addition of one or more additives, the conductivity of the rinse solution can be adjusted to a predetermined value. The conductivity of the rinse solution after adding one or more additives may be about 0.1 mS / cm or more, about 0.2 mS / cm or more, about 0.3 mS / cm or more, or about 0.4 mS / cm or more, and preferably about 0.5 mS / cm or more. To promote rapid charge transfer between the substrate and the rinse solution, a conductivity of about 0.5 mS / cm or more is preferred. For example, the conductivity of the rinse solution after adding one or more additives may be about 0.1 mS / cm to about 5 mS / cm, about 0.2 mS / cm to about 4 mS / cm, about 0.3 mS / cm to about 3 mS / cm, about 0.4 mS / cm to about 2.5 mS / cm, or about 0.45 mS / cm to about 2 mS / cm.

[0073]

[0082] The IEP depends on the pK1 and pK2 of the outer surface composition. For example, for SiO2 hydroxide, pK1 = 6, and for SiOH, pK2 = -2. IEP = (pK1 + pK2) / 2, so the IEP value for SiO2 is 2 to 3. For Si3N4, pK1 and pK2 are 8 and 5 to 6 respectively, so the IEP is 6 to 7.

[0074]

[0083] Therefore, rinsing with H2O or CO2 / H2O having a pH of 4-6 results in positively charged Si3N4 and negatively charged SiO2. The conductivity of H2O is 0.004 mS / cm, while the conductivity of the CO2 / H2O system is 0.02 mS / cm. Consequently, because the pH of the CO2 / H2O rinsing solution is not sufficiently low, CO2 / H2O cannot prevent the charging of SiO2-based wafers.

[0075]

[0084] In contrast, by adding acetic acid (CH3COOH), a slightly stronger acid, a rinse solution with pH > 3 and conductivity > 0.7 mS / cm can be achieved. Rinsing the SiO2 surface with a pH 2.9 rinse solution does not result in a net change in the charge on the substrate surface (see Figure 5). On the Si3N4 surface, the total charge decreases (see Figure 6).

[0076]

[0085] Conversely, rinsing the SiO2 substrate with an acetic acid / water rinse solution adjusted to pH 4.9 (conductivity 0.0046 mS / cm) results in the substrate becoming negatively charged.

[0077]

[0086] Specifically, Figure 5a shows the effect on charge when the back surface of the substrate is rinsed with CH3COOH / H2O, H2O, and CO2 / H2O while the rinsing solution is supplied at a spin speed of 2400 rpm for 18 seconds and then dried at 2400 rpm for 20 seconds. The rinsing solution is supplied at a distance of d=80 mm from the center onto a rotating 150 nm thick thermal SiO2 layer on the wafer. The GRIP method is used, in which the core is electrically grounded using mechanical contact points within the wafer core while the potential is recorded using an electrostatic voltmeter (ESVM). Data for an unrinsed substrate is also included for reference. Figure 5b shows the same graph as Figure 5a but with a different y-axis scale, indicating that rinsing with acetic acid solution results in an uncharged substrate.

[0078]

[0087] Figure 6 shows the effect on charge when the back surface of the substrate is rinsed with only CH3COOH / H2O versus H2O while the rinsing solution is supplied at a spin speed of 2400 rpm for 18 seconds and then dried at 2400 rpm for 20 seconds. The rinsing solution is supplied to the back surface of a rotating 60 nm LPCVD Si3N4 coated wafer at a distance of d=80 mm from the center.

[0079]

[0088] Figure 7 shows the effects of rinsing a pre-charged SiO2 wafer with water at 2000 rpm and then with acetic acid at 2400 rpm. The result shows a significant reduction in charge due to the acetic acid rinse. A 150 nm thick SiO2 layer on the back surface of the wafer was charged using water. When the back surface of the wafer was rinsed with a pH=2.9 CH3COOH / H2O solution at 2400 rpm for 18 seconds and then dried at 2400 rpm for 20 seconds, the charge on the back surface of the SiO2 wafer decreased.

[0080]

[0089] Figure 8 shows the decrease in charge when a charged wafer is cleaned with a CH3COOH / H2O solution.

[0081]

[0090] The specific method used to control the addition of one or more additives to the rinse solution based on one or more measurements is not particularly limited, as long as the pH and / or conductivity of the rinse solution reaches a predetermined value. For example, one or more additives may be added to the rinse solution to adjust the pH and / or conductivity of the rinse solution to a predetermined value. The addition of one or more additives to the rinse solution can be stopped to adjust the pH and / or conductivity of the rinse solution to a predetermined value. The number of additives added can be adjusted to increase or decrease the number of additives added. The pH and / or conductivity of the rinse solution can be changed by increasing or decreasing the concentration, pH, amount, and / or pressure of one or more additives. The compounds of one or more additives can also be changed to change the pH and / or conductivity of the rinse solution (for example, by replacing a very weak organic acid additive such as phenol with a carboxylic acid additive). The time over which one or more additives are added may be increased and / or decreased. If the pH and / or conductivity of the rinse solution are already at a predetermined value, controlling the addition of one or more additives may mean not changing the addition of one or more additives in order to maintain the pH and / or conductivity of the rinse solution at a predetermined value.

[0082]

[0091] The method of the present invention may further include measuring one or more properties of the rinse solution after adding one or more additives to the rinse solution. For example, the pH of the rinse solution may be measured after adding one or more additives in step c). Alternatively or additionally, the conductivity of the rinse solution may be measured after adding one or more additives in step c). Following this measurement, the method may further control the addition of one or more additives to the rinse solution based on the measurement to adjust the pH value and / or conductivity of the rinse solution to predetermined values. For example, one or more further additives may be added to the rinse solution.

[0083]

[0092] One or more additives can be introduced into the rinse fluid by any method known in the art. For example, one or more additives may be introduced into the rinse fluid by operating one or more control valves.

[0084]

[0093] The method of the present invention may further include spinning the substrate while the rinsing solution is being applied to a first surface of the substrate. For example, the substrate can be spun at about 1000 rpm to about 3000 rpm, about 1200 rpm to about 2800 rpm, about 1400 rpm to about 2600 rpm, or about 1600 rpm to about 2400 rpm.

[0085]

[0094] The method of the present invention may further include adapting the hydraulic pressure of the rinsing fluid or the rotational speed at which the substrate spins during rinsing based on the value of a characteristic measured in step b), for example, the charge on the substrate. Based on the measured characteristic, the hydraulic pressure of the rinsing fluid can be increased or decreased. Based on the measured characteristic, the rotational speed of the substrate can be increased or decreased.

[0086]

[0095] The method of the present invention may further include adapting the radial position of the rinse solution as it is applied to the first surface of the substrate while the substrate is rotating (spinning) around the axis of rotation, which is the axis of rotation of the substrate during spinning. Furthermore, the composition of the rinse solution can be adapted as a function of the radial position. Thus, one or more additives can be introduced into the rinse solution as a function of the radial position of the rinse solution as it is applied to the substrate.

[0087]

[0096] The substrate can be made from any semiconductor material known in the art that can be used in the manufacture of the substrate. For example, the substrate may be a silicon wafer, silicon nitride wafer, silicon oxide wafer, silicon carbide wafer, gallium nitride wafer, gallium arsenide wafer, or aluminum titanium carbide wafer. Preferably, the substrate is a silicon wafer, silicon nitride wafer, or silicon oxide wafer. The substrate may contain one or more substrate coatings, as long as the rinsing solution does not react with or dissolve one or more coatings. One or more coatings may include carbon-based polymer coatings.

[0088]

[0097] The present invention also provides a system that can be used to carry out the methods discussed herein. In particular, the present invention provides a system for processing a substrate, the system comprising: a) a support for supporting the substrate; b) a nozzle positioned to provide a rinse solution to a first surface of the substrate; c) a measuring system configured to measure the properties of the substrate and / or the rinse solution; and d) a controller configured to adjust the pH value and / or conductivity of the rinse solution based on the measurements of the measuring system by controlling the addition of one or more additives to the rinse solution.

[0089]

[0098] According to the present invention, the system may comprise one or more nozzles arranged to provide a rinse solution to the substrate surface. Each of the one or more nozzles may provide a different rinse solution. For example, a first nozzle may provide a first rinse solution, and a second nozzle may provide a second rinse solution. The first and second rinse solutions may have different properties. The first and second rinse solutions may have the same properties. The one or more nozzles can be arranged in a 1D or 2D array.

[0090]

[0099] The position of each of the one or more nozzles can be controlled by a controller located within the system. That is, the position of each of the one or more nozzles relative to the substrate, for example, its position relative to the center of the substrate, can be controlled by the controller. Thus, the position of each of the one or more nozzles can be defined as a radial position, which is its position relative to the axis of rotation of the substrate while the substrate is spinning. By changing the radial position of the nozzles while supplying rinsing fluid to the substrate (while the substrate is spinning), the entire area of ​​interest can be supplied with (and covered) the rinsing fluid.

[0091]

[0100] The position of one or more nozzles can be set or defined by the spatial properties of the substrate. This is a mapping of (local) charges on the substrate, which can form a charge map on the substrate.

[0092]

[0101] The system can be configured to measure at least one of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The system can be configured to measure at least two of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The system can be configured to measure at least three of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. The system can be configured to measure all of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. For example, the system can be configured to measure the charge on the substrate. Alternatively, the system can be configured to measure the isoelectric point (IEP) of a first surface of the substrate when in contact with water. Alternatively, the system can be configured to measure the pH value of the rinse solution. Alternatively, the system can be configured to measure the conductivity of the rinse solution. The system can be configured to measure both the charge on the substrate and the isoelectric point (IEP) of a first surface of the substrate when in contact with water. The system can be configured to measure both the charge on the substrate and the pH value of the rinse solution. The system can be configured to measure both the isoelectric point (IEP) of a first surface of the substrate when in contact with water and the pH value of the rinse solution. The system can be configured to measure both the charge on the substrate and the conductivity of the rinse solution. The system can be configured to measure both the pH value of the rinse solution and the conductivity of the rinse solution. The system can be configured to measure both the isoelectric point (IEP) of a first surface of the substrate when in contact with water and the conductivity of the rinse solution.

[0093]

[0102] The nozzle is positioned to supply the rinse solution to a first surface of the substrate. Therefore, the system of the present invention can be used to clean the first surface of the substrate using the rinse solution. The nozzle can be positioned to supply the rinse solution to the back or front surface of the substrate. Preferably, the nozzle is positioned to supply the rinse solution to the back surface of the substrate. Therefore, the system of the present invention is preferably used to clean the back surface of the substrate using the rinse solution.

[0094]

[0103] The system can be configured to measure characteristics on the back surface of a substrate. Thus, the charge can be measured at one or more points (or locations) on the back surface of the substrate. If the IEP on a first surface of the substrate is measured when it comes into contact with water, the first surface may be the back surface of the substrate.

[0095]

[0104] The system can be configured to measure a spatial profile based on the charge measurement of the substrate. Thus, a mapping of (local) charge on the substrate, i.e., a charge map, can be obtained. Alternatively, the system can be configured to measure one or more point charges at one or more points on the surface of the substrate. The measurement system may include any suitable device for measuring charge, such as an electrostatic voltmeter.

[0096]

[0105] The measurement system may include any suitable device for measuring the properties of the substrate. For example, the measurement system may include an FTIR (Fourier Transform Infrared) spectrometer, which can be used to determine the composition of the substrate and then estimate or calculate the IEP of the first surface of the substrate when it comes into contact with water. The measurement system may include a pH sensor or probe for calculating the pH of the rinse solution. The measurement system may include a device suitable for measuring electric charge, such as an electrostatic voltmeter. The measurement system may include a sensor for measuring conductivity, such as an electrical conductivity meter.

[0097]

[0106] The rinsing solution and one or more additives may be as defined above in relation to the method of the present invention.

[0098]

[0107] The system of the present invention allows control over the addition of one or more additives to adjust the pH value and / or conductivity of the rinse solution to predetermined values. The values ​​are predetermined based on factors including 1) the isoelectric point of the specific substrate used and its surface, 2) whether it is intended to remove, add, or retain existing charges on the substrate, and 3) the sign and location of any existing charges on the substrate. For example, the predetermined pH value may be about 1 to about 4.5, about 2 to about 3.5, or about 2.5 to about 3. Alternatively, the predetermined pH value may be about 1.5 to about 2.5, about 2.5 to about 3.5, or about 3.5 to about 4.5. For example, the predetermined conductivity value may be about 0.1 mS / cm or more, about 0.2 mS / cm or more, about 0.3 mS / cm or more, or about 0.4 mS / cm or more, preferably about 0.5 mS / cm or more. For example, the predetermined conductivity values ​​may be approximately 0.1 mS / cm to approximately 5 mS / cm, approximately 0.2 mS / cm to approximately 4 mS / cm, approximately 0.3 mS / cm to approximately 3 mS / cm, approximately 0.4 mS / cm to approximately 2.5 mS / cm, or approximately 0.45 mS / cm to approximately 2 mS / cm.

[0099]

[0108] By controlling the addition of one or more additives, the conductivity of the rinse solution can be adjusted to a predetermined value.

[0100]

[0109] The system of the present invention may further include a second measuring system configured to measure one or more properties of the rinse solution after the addition of one or more additives to the rinse solution. For example, the second measuring system may be configured to measure the pH of the rinse solution after the addition of one or more additives to the rinse solution. Alternatively or additionally, the second measuring system may be configured to measure the conductivity of the rinse solution after the addition of one or more additives.

[0101]

[0110] The system may include one or more actuators and one or more control valves. One or more control valves may be configured to control the addition of one or more aqueous additives to the rinse solution.

[0102]

[0111] The system of the present invention can be configured to spin a substrate while a rinsing solution is being applied to a first surface of the substrate. For example, the system can be configured to spin the substrate at approximately 1000 rpm to 3000 rpm, approximately 1200 rpm to 2800 rpm, approximately 1400 rpm to 2600 rpm, or approximately 1600 rpm to 2400 rpm. The system can be configured to adjust the rotational speed based on measurements from a measuring system. The rotational speed of the substrate can be increased or decreased based on the characteristics being measured.

[0103]

[0112] The system of the present invention can be configured to adjust the hydraulic pressure of the rinse fluid based on measurements from a measuring system. Based on the characteristics being measured, the hydraulic pressure of the rinse fluid can be increased or decreased.

[0104]

[0113] The substrate can be made from any semiconductor material known in the art that can be used in the manufacture of the substrate. For example, the substrate may be a silicon wafer, silicon nitride wafer, silicon oxide wafer, silicon carbide wafer, gallium nitride wafer, gallium arsenide wafer, or aluminum titanium carbide wafer. Preferably, the substrate is a silicon wafer, silicon nitride wafer, or silicon oxide wafer. The substrate may contain one or more substrate coatings, as long as the rinsing solution does not react with or dissolve one or more coatings. One or more coatings may include carbon-based polymer coatings.

[0105]

[0114] In the embodiment shown in Figure 9, step 1 uses an electrostatic voltmeter 92 to determine the charge 91 inside or on the surface of the Si wafer. In step 2, based on the measurement of the electrostatic voltmeter 92, a control valve 95 is used to add a liquid additive 94 to the water supply 93. The resulting rinse solution 96 is then used to rinse the back surface of the wafer. For example, the resulting charge map can be used to control the properties of the rinse solution. Thus, the properties of the rinse solution can vary as a function of the position (or location) on the wafer surface.

[0106]

[0115] In the embodiment shown in Figure 10, step 1 uses an electrostatic voltmeter 102 to determine the charge 101 inside or on the surface of the Si wafer. FTIR 103 is used to provide information about the wafer structure. This information, along with information from previous manufacturing steps, is used to determine how much liquid additives 105, 106 need to be added to the feedwater 104 to produce the rinse solution 109. In step 2, based on the measurements made in step 1, two control valves 107, 108 are used to add the two liquid additives 105, 106 to the feedwater 104. The back surface of the wafer is then rinsed with the rinse solution 109. It will be understood by those skilled in the art that the number of additives is not limited to two. Multiple additives can also be used for the same purpose.

[0107]

[0116] One or more valves may be controlled by controllers located within the system.

[0108]

[0117] The system may be part of a larger apparatus. For example, the system may be part of an apparatus used for manufacturing integrated circuits. The system may be part of an apparatus configured to move a substrate into a lithography apparatus. The system can be used to clean the substrate immediately before moving it into the lithography apparatus. Therefore, the system may be part of a wafer track. Furthermore, the system may be a standalone system.

[0109]

[0118] The present invention also provides a method for manufacturing devices such as integrated circuits. The method for manufacturing the device includes processing a substrate as described herein.

[0110]

[0119] Aspects of the present invention are described in the following clauses. 1. A method for processing a substrate, comprising: a) providing the substrate on a support; b) measuring the properties of the substrate and / or a rinse solution; c) controlling the addition of one or more additives to the rinse solution based on the measurement to adjust the pH value and / or conductivity of the rinse solution to a predetermined value; and d) providing the rinse solution to a first surface of the substrate through one or more nozzles. 2. The method according to Clause 1, wherein the characteristics to be measured are at least one of (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. 3. The method according to Clause 1 or 2, wherein the characteristics to be measured are at least two of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. 4. The method according to any one of the claims 1 to 3, wherein in step d), the rinsing solution is provided on the back surface of the substrate. 5. The method according to any of the provisions 1 to 4, wherein in step b), the charge on the back surface of the substrate is measured. 6. The method according to any of the clauses 1 to 5, wherein in step b), a spatial profile is measured based on the charge measurement of the substrate. 7. The measurement in step b) is performed using an electrostatic voltmeter and / or an FTIR (Fourier Transform Infrared) spectrometer, as described in any of clauses 1 to 6. 8. In step d), providing a rinse solution to the surface of the substrate reduces the charge on the substrate, according to any of the methods in clauses 1 to 7. 9. The method according to any of the clauses 1 to 7, wherein in step d), providing a rinse solution to the surface of the substrate does not substantially affect the charges on the substrate. 10. The rinse solution is an aqueous solution, as described in any of the methods in paragraphs 1 to 9. 11. The method according to any of the provisions 1 to 10, wherein one or more additives are aqueous solutions. 12. The method according to any one of the provisions 1 to 11, wherein one or more additives include one or more organic acids. 13. The method according to Clause 12, wherein one or more organic acids contain 1 to 10 carbon atoms. 14. The method according to clause 12 or 13, wherein one or more organic acids comprise at least one compound having at least one group selected from a carboxyl group, a sulfo group, a thiol group, an alcohol group, an enol group, and a phenol group. 15. One or more organic acids include formic acid, acetic acid, glycolic acid, glyoxylic acid, oxalic acid, propionic acid, acrylic acid, propiolic acid, lactic acid, 3-hydroxypropionic acid, glyceric acid, pyruvate, 3-oxopropanoic acid, 2,3-dioxopropanoic acid, malonic acid, tartonic acid, 2,2-dihydroxypropanediic acid, mesooxalic acid, glycidic acid, butyric acid, isobutyric acid, crotonic acid, isocrotonic acid, methacrylic acid, vinylacetic acid, tetrolic acid, acetoacetic acid, succinic acid The method according to any one of the following, comprising at least one of the following: acids, fumaric acid, maleic acid, malic acid, tartaric acid, oxaloacetate, valeric acid, caproic acid, citric acid, aconitic acid, isocitric acid, sorbic acid, enanthic acid, pimelic acid, benzoic acid, salicylic acid, caprylic acid, phthalic acid, softalic acid, terephthalic acid, pelargonic acid, trimesic acid, cinnamic acid, capric acid, sebacic acid, glutaric acid, adipic acid, pimelic acid, trifluoroacetic acid, and uric acid. 16. The method according to any one of the claims 12 to 15, wherein one or more organic acids comprise at least one compound containing a carboxyl group. 17. One or more organic acids comprising 1 to 3 carbon atoms, as described in any of the methods in clauses 12 to 16. 18. The method according to any one of the clauses 12 to 17, wherein one or more organic acids include at least one of formic acid, acetic acid, or propionic acid. 19. The method according to any one of the clauses 12 to 18, wherein one or more organic acids include acetic acid. 20. One or more organic acids having a boiling point of approximately 80°C to approximately 150°C at a pressure of 1 atmosphere, as described in any of clauses 12 to 19. 21. The method according to any one of the claims 1 to 20, wherein in step c), one or more additives are introduced into the rinse fluid by activating one or more control valves. 22. The method according to any one of the provisions 1 to 21, further comprising measuring the pH of the rinse solution after adding one or more additives in step c). 23. The method according to any one of the clauses 1 to 22, wherein in step c), the pH value of the rinse solution is adjusted to a predetermined value, the predetermined pH value being approximately 1 to approximately 4.5, optionally approximately 1 to approximately 3, or optionally approximately 1 to approximately 2. 24. In step c), the conductivity of the rinse solution is adjusted to a predetermined value, the predetermined conductivity value being greater than approximately 0.1 mS / cm, according to any of the methods in clauses 1 to 23. 25. In step c), the conductivity of the rinse solution is adjusted to a predetermined value, the predetermined conductivity value being greater than approximately 0.5 mS / cm, according to any of the methods in clauses 1 to 24. 26. The method according to any one of the claims 1 to 25, wherein the substrate is a silicon wafer, silicon nitride wafer, silicon oxide wafer, silicon carbide wafer, gallium nitride wafer, gallium arsenide wafer, or titanium aluminum carbide wafer, preferably the substrate is a silicon wafer, silicon nitride wafer, or silicon oxide wafer. 27. A system for processing a substrate, comprising: a) a support for supporting the substrate; b) one or more nozzles arranged to provide a rinse solution to a first surface of the substrate; c) a measuring system configured to measure the properties of the substrate and / or the rinse solution; and d) a controller configured to adjust the pH value and / or conductivity of the rinse solution based on measurements by the measuring system by controlling the addition of one or more additives to the rinse solution. 28. The measurement system according to Clause 27, configured to measure at least one of (i) the electric charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. 29. The measurement system according to Clause 27 or 28, configured to measure at least two of the following: (i) the electric charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution. 30. The system according to any one of the clauses 27 to 29, wherein each of the one or more nozzles is positioned to provide rinsing fluid to the back surface of the substrate. 31. The measurement system is one of the systems described in any of clauses 27 to 30, configured to measure the charge on the back surface of a substrate. 32. The measurement system is configured to provide a spatial profile based on the charge measurement of the substrate, as described in any of clauses 27 to 31. 33. The measurement system is a system described in any of clauses 27 to 32, including an electrostatic voltmeter and / or an FTIR (Fourier Transform Infrared) spectrometer. 34. The rinse solution is an aqueous solution, as described in any of clauses 27-33 of the system. 35. One or more additives are aqueous solutions, as described in any of clauses 27 to 34. 36. A system as described in any of clauses 27 to 35, wherein one or more additives include one or more organic acids. 37. The system according to any one of the clauses 27 to 36, comprising one or more actuators and one or more control valves, each of which is configured to control the addition of one or more aqueous additives to the rinse fluid. 38. The system according to any one of the clauses 27 to 37, wherein the substrate is a silicon wafer, silicon nitride wafer, silicon oxide wafer, silicon carbide wafer, gallium nitride wafer, gallium arsenide wafer, or titanium aluminum carbide wafer, preferably the substrate is a silicon wafer, silicon nitride wafer, or silicon oxide wafer. 39. A system as described in any of Clauses 27 to 38, wherein the system is part of an apparatus configured to move a substrate into a lithography apparatus. 40. A method for manufacturing a device, including a method for processing a substrate as described in any of clauses 1 to 26.

[0111]

[0120] While the present invention has been described in relation to various embodiments, other embodiments will be apparent to those skilled in the art from considering the details and practices of the invention disclosed herein. This specification and examples are intended to be merely illustrative, and the true scope and spirit of the invention are shown in the following claims.

Claims

1. A method for processing a substrate, a) Providing the substrate on a support, b) Measuring the characteristics of the substrate and / or the rinse solution, c) Controlling the addition of one or more additives to the rinse solution based on the measurement to adjust the pH value and / or conductivity of the rinse solution to a predetermined value, d) Providing the rinsing liquid to the first surface of the substrate through one or more nozzles Methods that include...

2. The method according to claim 1, wherein the characteristic to be measured is at least one of (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution.

3. The method according to claim 1 or 2, wherein the characteristics to be measured are at least two of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution.

4. The method according to any one of claims 1 to 3, wherein in step d), the rinsing liquid is provided on the back surface of the substrate.

5. The method according to any one of claims 1 to 4, wherein in step b), the charge on the back surface of the substrate is measured.

6. The method according to any one of claims 1 to 5, wherein in step b), a spatial profile based on the charge measurement of the substrate is measured.

7. The method according to any one of claims 1 to 6, wherein the measurement in step b) is performed using an electrostatic voltmeter and / or an FTIR (Fourier transform infrared) spectrometer.

8. The method according to any one of claims 1 to 7, wherein in step d), providing the rinsing liquid to the surface of the substrate reduces the charge on the substrate.

9. The method according to any one of claims 1 to 8, wherein the one or more additives comprises one or more organic acids.

10. The method according to claim 9, wherein the one or more organic acids comprise at least one compound comprising at least one group selected from a carboxyl group, a sulfo group, a thiol group, an alcohol group, an enol group, and a phenol group.

11. A system for processing substrates, a) A support for supporting the substrate, b) One or more nozzles arranged to provide rinsing liquid to the first surface of the substrate, c) A measurement system configured to measure the properties of the substrate and / or the rinse solution, d) A system comprising a controller configured to adjust the pH value and / or conductivity of the rinse solution based on measurements by the measuring system by controlling the addition of one or more additives to the rinse solution.

12. The system according to claim 11, wherein the measurement system is configured to measure at least one of (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution.

13. The measurement system according to claim 11 or 12, wherein the measurement system is configured to measure at least two of the following: (i) the charge on the substrate, (ii) the isoelectric point (IEP) of the first surface of the substrate when in contact with water, (iii) the pH value of the rinse solution, and (iv) the conductivity of the rinse solution.

14. The system according to any one of claims 11 to 13, wherein each of the one or more nozzles is arranged to provide the rinsing liquid to the back surface of the substrate.

15. The measurement system is configured to measure the charge on the back surface of the substrate, according to any one of claims 11 to 14.

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