Method of processing a substrate

Abstract

The present invention relates to a method of processing a substrate having one side and a side opposite the one side. In particular, the present invention relates to a method comprising providing a protective film having a front surface and a back surface opposite the front surface; and applying a coating of a water-soluble material to at least a central region of the front surface of the protective film and / or applying a coating of a water-soluble material to at least a central portion of the one side of the substrate. Then, the protective film is applied to the one side of the substrate with the front surface of the protective film facing the one side of the substrate and without an adhesive between at least the central region of the front surface of the protective film and the one side of the substrate. Further, the method comprises applying an external stimulus to the protective film during and / or after applying the protective film to the one side of the substrate such that the protective film is attached to the one side of the substrate and processing the one side of the substrate and / or the side of the substrate opposite the one side.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to German patent application No. 10 2021 209979.3 filed with the German Patent and Trademark Office on 9 September 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a method for processing a substrate (such as a wafer) having a side side and a side opposite to the side side. Background Technology

[0004] The processing of substrates (such as wafers) must typically be performed with high efficiency and reliability. For example, in device manufacturing processes, such as those used to produce semiconductor devices, a substrate (such as a wafer) with device regions (typically divided by multiple cleaving lines) is diced into individual dies. This manufacturing process typically includes a grinding step to adjust the substrate thickness, and a dicing step to cut the substrate along the cleaving lines to obtain individual dies. The grinding step is performed from the rear side of the substrate, opposite to the front side where the device regions are formed. Additionally, other processing steps, such as polishing and / or etching, may be performed on the rear side of the substrate. The substrate can be diced from either the front or rear side along the cleaving lines.

[0005] To protect devices formed on the substrate from damage, deformation and / or contamination, such as by debris, grinding water or cutting water, during substrate processing, a protective film or sheet can be applied to the front side of the substrate before processing.

[0006] This protection is particularly important if the device region has an uneven surface structure. For example, in known semiconductor device manufacturing processes such as wafer-level chip-scale package (WLCSP), the device region of the substrate is formed with multiple protrusions (e.g., bumps) projecting from the flat surface of the substrate. These protrusions are used, for example, to establish electrical contact with the device in a single die, such as when the die is incorporated into an electronic device such as a mobile phone or personal computer.

[0007] To achieve this size reduction in electronic devices, the semiconductor devices must be reduced in size. Therefore, in the grinding step mentioned above, the substrate on which the devices are formed is ground to a thickness in the μm range (e.g., in the range of 20 μm to 100 μm).

[0008] In known semiconductor device manufacturing processes, the presence of protrusions (e.g., bumps) in the device region can cause problems during processing (e.g., during a grinding step). More specifically, the risk of substrate breakage during processing is significantly increased due to the presence of these protrusions. Furthermore, if the substrate is ground to a small thickness (e.g., in the μm range), protrusions in the device region on the front side of the substrate can cause deformation on the rear side of the substrate, thus reducing the quality of the resulting die.

[0009] Therefore, the use of protective films or sheets is particularly important when processing substrates with device areas having such uneven surface structures.

[0010] However, especially for sensitive devices such as micro-electro-mechanical systems (MEMS), the problem is that when the film or sheet is peeled off from the substrate, the device structure on the substrate may be damaged by the adhesive force of the adhesive layer formed on the protective film or sheet, or may be contaminated by adhesive residues on the device.

[0011] For example, in order to protect the substrate from damage, deformation and / or contamination such as debris during the substrate cutting step, a protective film or sheet may be applied to the back side of the substrate before processing.

[0012] In the same situation, the following problems exist: when peeling the film or sheet from the substrate, the substrate may be damaged by the adhesive force of the adhesive layer formed on the protective film or sheet, or may be contaminated by adhesive residue on the substrate.

[0013] To address this issue, DE 10 2018 200 656 A1 proposes applying a protective film to the wafer such that at least the central region of the protective film is in direct contact with the wafer. Application through external stimulation creates adhesion between the protective film and the wafer, which holds the protective film in its position on the wafer. However, while this method avoids adhesive residue on the wafer, it cannot rule out the possibility that residue of the protective film material may remain on the substrate after peeling off. Furthermore, if the adhesion between the protective film and the wafer is strong, the protective film may be difficult to peel off from the wafer.

[0014] Therefore, there is still a need for a reliable and efficient method for processing substrates that allows for minimizing the risk of any contamination and damage to the substrates. Summary of the Invention

[0015] Therefore, one object of the present invention is to provide a reliable and efficient method for processing a substrate, which minimizes any risk of contamination and damage to the substrate. This object is achieved by a substrate processing method having the technical features of the first aspect of the invention, and by a substrate processing method having the technical features of the second aspect of the invention. Preferred embodiments of the invention will be derived from other aspects of the invention.

[0016] According to a first aspect, the present invention provides a method for processing a substrate having one side and a side opposite to the one side. The method includes: providing a protective film having a front surface and a rear surface opposite to the front surface; and applying a water-soluble material coating to at least a central region of the front surface of the protective film, and / or applying a water-soluble material coating to at least a central portion of one side of the substrate. The method further includes: after applying the coating to the protective film, and / or after applying the coating to the substrate, applying the protective film to one side of the substrate, wherein the front surface of the protective film faces one side of the substrate, and the application of the protective film results in no adhesive between at least a central region of the front surface of the protective film and one side of the substrate. Furthermore, the method includes: during and / or after applying the protective film to one side of the substrate, applying an external stimulus to the protective film, causing the protective film to attach to one side of the substrate; and processing one side of the substrate and / or the side of the substrate opposite to the one side.

[0017] A protective film is applied to one side of a substrate such that no adhesive is present between at least a central region of the front surface of the protective film and one side of the substrate. Therefore, the risk of potential contamination or damage to the substrate, such as due to the adhesive force of the adhesive layer or adhesive residue on the substrate, can be significantly reduced or even eliminated. No adhesive is required between at least a central portion of the front surface of the protective film and one side of the substrate.

[0018] During and / or after applying the protective film to one side of the substrate, an external stimulus is applied to the protective film, causing it to adhere to one surface of the substrate. The application of the external stimulus creates an adhesion force between the protective film and the substrate, which holds the protective film in place on the substrate. Therefore, no additional adhesive material is necessary to attach the protective film to one side of the substrate.

[0019] Specifically, by applying external stimuli to the protective film, shape fit (such as a positive fit) and / or material bond (such as an adhesive bond) can be formed between the protective film and the substrate. The terms "material bond" and "adhesive bond" define the attachment or connection between the protective film and the substrate due to atomic and / or molecular forces acting between the two components.

[0020] The term "adhesive bonding" refers to the presence of atomic and / or molecular forces that allow the protective film to attach or adhere to the substrate, and does not imply the presence of additional adhesive between the protective film and the substrate. Rather, as detailed above, there is no adhesive between at least the central region of the front surface of the protective film and one side of the substrate.

[0021] Before applying the protective film to one side of the substrate, a water-soluble coating is applied to at least a central region of the front surface of the protective film and / or to at least a central portion of one side of the substrate. The water-soluble coating may be applied only to at least a central region of the front surface of the protective film. The water-soluble coating may be applied only to at least a central portion of one side of the substrate. The water-soluble coating may be applied to at least a central region of the front surface of the protective film and at least a central portion of one side of the substrate.

[0022] The central region of the front surface of the protective film may correspond to at least the central portion of one side of the substrate.

[0023] The water-soluble coating can be applied to the entire front surface of the protective film. The entire portion of the front surface of the protective film is in direct contact with one side of the substrate. The water-soluble coating can be applied to the entire side of the substrate. The entire portion of one side of the substrate is in direct contact with the front surface of the protective film.

[0024] Water-soluble materials are not adhesives. As detailed above, there is no adhesive between at least the central region of the front surface of the protective film and one side of the substrate.

[0025] By applying a water-soluble material as a coating between the protective film and the substrate, at least in the central region or portion, the removal of the protective film from the substrate is significantly facilitated. In particular, the water-soluble material reduces the peeling force required to remove the protective film. Therefore, the risk of any damage to the substrate during the process of removing the protective film from the substrate is further reduced.

[0026] Furthermore, the presence of water-soluble materials minimizes the risk of any residue of the protective film material remaining on the substrate after removal. Due to the water-soluble nature of this material, if any residue remains on the substrate after removing the protective film, it can be removed simply, reliably, and effectively by cleaning one side of the substrate with water.

[0027] By applying a water-soluble coating to the protective film, a particularly complete and uniform coating can be obtained. Furthermore, the coating can be inspected in a particularly simple, reliable, and effective manner (e.g., visual inspection).

[0028] Therefore, the method of the first aspect of the present invention can reliably and efficiently process the substrate, minimizing any risk of contamination and damage to the substrate.

[0029] According to a second aspect, the present invention also provides a method for processing a substrate having one side and a side opposite to the one side. The method includes: providing a protective film having a front surface and a rear surface opposite to the front surface, wherein the protective film has a coating of a water-soluble material applied to at least a central region of the front surface of the protective film; and applying the protective film to one side of the substrate, wherein the front surface of the protective film faces one side of the substrate, and the application of the protective film results in no adhesive between at least a central region of the front surface of the protective film and one side of the substrate. The method further includes: during and / or after applying the protective film to one side of the substrate, applying an external stimulus to the protective film to attach the protective film to one side of the substrate; and processing one side of the substrate and / or the side of the substrate opposite to the one side.

[0030] The protective film may be pre-coated with a water-soluble material, for example, during or shortly after the manufacture of the protective film.

[0031] The substrate processing method according to the second aspect provides the technical effects and advantages that have been described in detail above with respect to the substrate processing method according to the first aspect.

[0032] The features described above for the substrate processing method according to the first aspect also apply to the substrate processing method according to the second aspect. In particular, the substrate, protective film, water-soluble material, and external stimuli can be the same as described above.

[0033] Therefore, the method of the second aspect of the present invention can also reliably and efficiently process the substrate, minimizing any risk of contamination and damage to the substrate.

[0034] The following features, definitions, technical effects, and advantages apply to the methods according to the first and second aspects.

[0035] One side of the substrate can be the front side or the rear side of the substrate. The side of the substrate opposite to one side can be the front side or the rear side of the substrate.

[0036] One side or surface of the substrate and the side or surface of the substrate opposite to that side or surface may be substantially parallel to each other.

[0037] The substrate can be made of, for example, semiconductors, glass, sapphire (Al2O3), ceramics (such as alumina ceramics, quartz, zirconium oxide, PZT (lead zirconate titanate), polycarbonate, or optical crystal materials.

[0038] Specifically, the substrate can be made of, for example, silicon carbide (SiC), silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), indium arsenide (InAs), indium phosphide (InP), silicon nitride (SiN), lithium tantalate (LT), lithium niobate (LN), aluminum nitride (AlN), or silicon oxide (SiO2).

[0039] The substrate can be a single crystal substrate, a glass substrate, a compound substrate (such as a compound semiconductor substrate, such as a SiC, SiN, GaN or GaAs substrate) or a polycrystalline substrate (e.g. a ceramic substrate).

[0040] The substrate can be a wafer. For example, the substrate can be a semiconductor-sized wafer. In this document, the term "semiconductor-sized wafer" refers to a wafer having the dimensions (normalized dimensions) of a semiconductor wafer, and particularly having the diameter (normalized diameter) (i.e., outer diameter) of a semiconductor wafer. The dimensions of the semiconductor wafer, particularly the diameter (i.e., outer diameter), are defined according to SEMI standards. For example, the dimensions of a polished single-crystal silicon (Si) wafer are defined according to SEMI standards M1 and M76. This semiconductor-sized wafer can be a 3-inch, 4-inch, 5-inch, 6-inch, 8-inch, 12-inch, or 18-inch wafer.

[0041] The substrate can be a semiconductor wafer. For example, the substrate can be made of any of the semiconductor materials given above.

[0042] The substrate (such as a wafer) can be made of a single material or a combination of different materials (e.g., two or more of the materials mentioned above). For example, the substrate can be a wafer bonded to Si and glass, wherein wafer elements made of Si are bonded to wafer elements made of glass.

[0043] The substrate can have any type of shape. In a top view of the substrate, the substrate can be, for example, circular, oval, elliptical, or polygonal (such as rectangular or square).

[0044] The substrate may have a device area with multiple devices on one side and / or on the side opposite to that side. The side of the substrate with the device area may be the front side of the substrate.

[0045] The devices in the device region can be, for example, semiconductor devices, power devices, optical devices, medical devices, electrical devices, MEMS devices, or combinations thereof. For example, a device may include or may be a transistor, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or a diode (e.g., Schottky barrier diodes).

[0046] On the side of the substrate with the device area, the substrate may also have a peripheral marginal area formed around the device area without any device.

[0047] One or more dividing lines may be formed on one side of the substrate and / or on the side of the substrate opposite to that side. If the substrate has a device region with multiple devices on one side of the substrate and / or on the side of the substrate opposite to that side, the devices may be divided by one or more dividing lines. The width of one or more dividing lines may be in the range of 30 μm to 200 μm, preferably 30 μm to 150 μm, and more preferably 30 μm to 100 μm.

[0048] A protective film can be applied to one side of a substrate to cover the device formed in the device area, thereby protecting the device from contamination and damage, for example.

[0049] The surface of one side of the substrate can be a generally flat, uniform surface or a flat, uniform surface. Alternatively, a protrusion or projection extending from the surface of the planar substrate along the thickness direction of the substrate, and / or a recess extending from the surface of the planar substrate along the thickness direction of the substrate, can be present on one side of the substrate. The thickness direction of the substrate extends from one side of the substrate toward a side of the substrate opposite to that side.

[0050] The external stimulus applied to the protective film may consist of or include: heating the protective film, and / or cooling the protective film, and / or applying pressure to the protective film, and / or applying a vacuum to the protective film, and / or irradiating the protective film with radiation (such as light or UV radiation) by using a laser beam.

[0051] External stimuli may include or may be compound and / or electronic or plasma irradiation, and / or mechanical processing (such as vacuum, pressure, friction or ultrasonic applications), and / or static electricity.

[0052] Particularly preferably, applying external stimulation to the protective film may consist of or include a heated protective film. For example, applying external stimulation to the protective film may consist of or include heating the protective film and applying a vacuum to the protective film. In this case, a vacuum may be applied to the protective film during and / or before and / or after heating the protective film.

[0053] If the external stimulus applied to the protective film is composed of or includes a heated protective film, the method may further include cooling the protective film after the heating process. Specifically, the protective film may be cooled to its initial temperature, i.e., to the temperature prior to its heating process. The protective film may be cooled to, for example, its initial temperature before processing one side of the substrate, and / or the side of the substrate opposite to that side.

[0054] An adhesion force is generated between the protective film and the substrate through a heating process. The attachment of the protective film to the substrate can occur during the heating process itself and / or in a subsequent process that cools the protective film.

[0055] For example, the protective film can be softened by a heating process so that it conforms to the substrate surface on one side of the substrate, for example, by allowing the protective film to adhere to the substrate's morphology. For example, the protective film can be re-hardened upon cooling (e.g., cooling to its initial temperature) to create a shape fit and / or material bond with the substrate.

[0056] The protective film can withstand temperatures up to 180°C or higher, preferably up to 220°C or higher, more preferably up to 250°C or higher, and even more preferably up to 300°C or higher.

[0057] The protective film can be heated to temperatures ranging from 30°C to 250°C, preferably from 50°C to 200°C, more preferably from 60°C to 150°C, and even more preferably from 70°C to 110°C. Particularly preferably, the protective film can be heated to a temperature of about 80°C.

[0058] The protective film may be heated during and / or after the application of the protective film to one side of the substrate for a duration ranging from 30 seconds to 10 minutes, preferably from 1 minute to 8 minutes, more preferably from 1 minute to 6 minutes, even more preferably from 1 minute to 4 minutes, and even more preferably from 1 minute to 3 minutes.

[0059] If the external stimulus applied to the protective film is composed of or includes a heating protective film, the protective film can be heated directly and / or indirectly.

[0060] The protective film can be heated by applying heat directly to it, for example, using a heat application device (such as a heated roller, a heated mold, etc.) or a heat radiation device. The protective film and substrate can be placed in a container or chamber (such as a vacuum chamber), and the internal volume of the container or chamber can be heated to heat the protective film. The container or chamber may be equipped with a heat radiation device.

[0061] Before and / or during and / or after applying the protective film to one side of the substrate, the protective film can be indirectly heated, for example, by heating the substrate. For example, the substrate can be heated by placing it on a support or carrier (such as a chuck stage) and heating the support or carrier.

[0062] For example, a support or carrier (such as a chuck table) can be heated to a temperature in the range of 30°C to 250°C, preferably 50°C to 200°C, more preferably 60°C to 150°C, and even more preferably 70°C to 110°C. Particularly preferably, the support or carrier can be heated to a temperature of about 80°C.

[0063] These methods can also be combined, for example, by using a heat application device (such as a heated roller) or a heat radiation device for directly heating the protective film, and also by a heat radiation device for indirectly heating the protective film via a substrate.

[0064] If the external stimulus applied to the protective film is composed of or includes a heat-generating protective film, then the protective film is preferably bendable, elastic, flexible, stretchable, soft, and / or compressible in its heated state. In this way, it can be reliably ensured that the protective film conforms to the substrate surface on one side of the substrate, for example, by allowing the protective film to adhere to the morphology of the substrate. This is particularly advantageous if protrusions (such as surface irregularities or roughness, bumps, optical elements, etc.) and / or recesses along the thickness direction of the substrate are present on one side of the substrate.

[0065] Preferably, the protective film hardens or stiffens to at least some extent upon cooling, becoming more rigid and / or more stable in the cooled state. In this way, the substrate can be reliably protected during subsequent processing.

[0066] The method may also include applying pressure to the rear surface of the protective film during and / or after applying the protective film to one side of the substrate. In this way, the front surface of the protective film is pressed against one side of the substrate. Therefore, reliable attachment of the protective film to the substrate can be ensured particularly effectively.

[0067] If applying external stimulation to the protective film includes heating the protective film, pressure can be applied to the rear surface of the protective film before and / or during and / or after heating the protective film. Pressure can be applied to the rear surface of the protective film before processing one side of the substrate and / or the side of the substrate opposite to that side.

[0068] Pressure can be applied to the back surface of the protective film using a pressure application device (such as a roller, a mold, a press film, etc.).

[0069] Particularly preferably, a combined hot-pressing application device, such as a heated roller or a heated die, can be used. In this case, the protective film can be heated while pressure is applied to the rear surface of the protective film.

[0070] Pressure can be applied to the rear surface of the protective film in a vacuum chamber, which will be described in more detail below.

[0071] The protective film can be applied and / or attached to one side of the substrate in a reduced pressure atmosphere (especially under vacuum). In this way, it can be reliably ensured that there are no voids and / or air bubbles between the protective film and the substrate. Therefore, any stress or strain on the substrate during substrate processing, such as due to the expansion of such air bubbles during heating processes, is avoided.

[0072] For example, one or more steps of applying and / or attaching a protective film to one side of a substrate can be performed in a vacuum chamber. Specifically, the protective film can be applied and / or attached to one side of the substrate using a vacuum laminator. In such a vacuum laminator, the substrate is placed on a chuck stage in the vacuum chamber with the side of the substrate opposite to one side in contact with the upper surface of the chuck stage, and one side of the substrate oriented upwards. The chuck stage can be, for example, a heated chuck stage.

[0073] The protective film to be applied to one side of the substrate is held at the periphery of the substrate in a vacuum chamber by an annular frame, and is positioned above one side of the substrate. An air inlet, sealed by an expandable rubber diaphragm, is provided in the upper part of the vacuum chamber located above the chuck stage and the annular frame.

[0074] After the substrate and protective film are loaded into the vacuum chamber, the chamber is evacuated, and air is supplied to the rubber diaphragm through an air inlet, causing the rubber diaphragm to expand into the evacuated chamber. In this way, the rubber diaphragm moves downwards within the vacuum chamber, pushing the protective film against one side of the substrate, thereby sealing the peripheral substrate portion with the protective film and compressing the film against one side of the substrate. Therefore, the protective film can be tightly applied to one side of the substrate to conform, for example, to the contour of a protrusion or bulge, if such a protrusion or bulge is present.

[0075] During and / or after the application of the protective film to one side of the substrate, the protective film can be heated, for example, by heating a chuck stage.

[0076] Subsequently, the vacuum in the vacuum chamber is released, and the protective film is held in place on one side of the substrate by the adhesion force generated by the heating process and the positive pressure in the vacuum chamber.

[0077] Alternatively, the rubber diaphragm can be replaced by a soft printing mold or a soft roller.

[0078] The protective film can have any type of shape. In a top view of the protective film, it can be, for example, circular, oval, elliptical, or polygonal (e.g., rectangular or square).

[0079] The protective film can have approximately the same shape as or the same shape as the substrate.

[0080] The protective film can have an outer diameter larger than that of the substrate. In this way, it can facilitate the processing, handling, and / or transportation of the substrate. In particular, the outer peripheral portion of the protective film can be attached to an annular frame, as will be detailed below.

[0081] The protective film can have an outer diameter smaller than that of the substrate.

[0082] The protective film can have an outer diameter that is substantially the same as that of the substrate.

[0083] The protective film can have an outer diameter that is substantially the same as or larger than the outer diameter of the substrate.

[0084] The method may further include: cutting the protective film. The protective film may be cut such that its outer diameter is greater than, smaller than, or substantially the same as the outer diameter of the substrate. Alternatively, the protective film may be cut such that its outer diameter is substantially the same as, or larger than, the outer diameter of the device region of the substrate.

[0085] The step of cutting the protective film can be performed before or after the protective film is applied to the substrate.

[0086] The step of cutting the protective film can be performed before or after attaching the protective film to the substrate.

[0087] The method may further include attaching the outer peripheral portion of the protective film to the annular frame. Specifically, the outer peripheral portion of the protective film may be attached to the annular frame such that the protective film closes the central opening of the annular frame, i.e., the region within the inner diameter of the annular frame. Thus, the annular frame holds the substrate attached to the protective film (more specifically, to the central portion of the protective film) through the protective film. Therefore, a substrate unit comprising the substrate, the protective film, and the annular frame is formed, thereby facilitating the processing, handling, and transport of the substrate.

[0088] The step of attaching the outer peripheral portion of the protective film to the annular frame can be performed before or after the protective film is applied to the substrate.

[0089] The step of attaching the outer peripheral portion of the protective film to the annular frame can be performed before or after attaching the protective film to the substrate.

[0090] The step of attaching the outer periphery of the protective film to the annular frame can be performed before or after processing one side of the substrate and / or the side of the substrate opposite to one side.

[0091] The protective film can be applied to one side of the substrate such that there is no adhesive between the front surface of the protective film and one side of the substrate in the entire area where the front surface of the protective film contacts one side of the substrate.

[0092] In this way, the risk of contamination or damage to the substrate, such as due to the adhesive force of the adhesive layer on the substrate or adhesive residue, can be reliably eliminated.

[0093] The entire front surface of the protective film can be without adhesive.

[0094] Alternatively, the protective film may have an adhesive layer disposed only in the peripheral region of the front surface of the protective film, which surrounds the central region of the front surface of the protective film, and the protective film is applied to one side of the substrate such that the adhesive layer contacts only the peripheral portion of one side of the substrate. The peripheral portion of one side of the substrate may surround the central portion of one side of the substrate. The peripheral portion of one side of the substrate may correspond to or be the peripheral edge region of the substrate.

[0095] By providing a protective film with an adhesive layer only in the peripheral region of the front surface of the protective film, the adhesion between the protective film and the substrate can be further improved. Since the adhesive layer is only provided in the peripheral region of the front surface of the protective film, the area through which the protective film and the substrate are attached to each other via the adhesive layer is significantly reduced compared to providing the adhesive layer on the entire front surface of the protective film. Therefore, the protective film can be more easily separated from the substrate, and the risk of damaging the substrate is significantly reduced, particularly the risk of damaging protrusions formed on one side of the substrate.

[0096] The adhesive layer can be cured by external stimuli such as UV radiation, electric fields, and / or chemical agents. This allows the protective film to be removed from the substrate particularly easily after processing. External stimuli can be applied to the adhesive to reduce its adhesive strength, thereby allowing easy removal of the protective film.

[0097] For example, the adhesive layer can have a generally annular shape, an open rectangular shape, or an open square shape, that is, a rectangular or square shape with an opening in the center of the adhesive layer, respectively.

[0098] The protective film can be stretchable. When the protective film is applied to one side of the substrate, it can stretch. If there are protrusions on one side of the substrate, when the protective film is applied to one side of the substrate, it can stretch to closely or at least partially conform to the contours of these protrusions.

[0099] Specifically, the protective film can be extended to more than twice its original size, preferably more than three times its original size, and more preferably more than four times its original size. In this way, especially when extended to more than three times its original size, the protective film can reliably ensure conformability to the contour of the protrusion.

[0100] Specifically, during the processing of one side of the substrate and / or the side of the substrate opposite to that one side, the protective film may be configured to protect one side of the substrate.

[0101] The protective film can be made from a single material, especially a single homogeneous material. The protective film can be, for example, a sheet or a foil.

[0102] The protective film can be made of plastic materials (e.g., polymers). Particularly preferred is that the protective film is made of polyolefin. For example, the protective film can be made of polyethylene (PE), polypropylene (PP), or polybutene (PB).

[0103] Polyolefin films possess material properties particularly advantageous for use in the substrate processing methods of the present invention, especially when the application of external stimulation to the protective film is performed by or includes a heat-resistant protective film. When heated (e.g., at temperatures in the range of 60°C to 150°C), they are flexible, stretchable, and pliable. Therefore, it can be reliably ensured that the protective film conforms to the substrate surface on one side of the substrate, for example, ensuring that the protective film adheres to the substrate morphology. This is particularly advantageous if one side of the substrate has a protrusion projecting from the plane of the substrate.

[0104] Furthermore, the polyolefin film hardens and stiffens upon cooling, becoming more rigid and stable in the cooled state. This ensures particularly reliable protection of the substrate during subsequent processing.

[0105] The protective film may have a thickness ranging from 5 μm to 500 μm, preferably from 5 μm to 200 μm, more preferably from 8 μm to 100 μm, even more preferably from 10 μm to 80 μm, and still even more preferably from 12 μm to 50 μm. Particularly preferably, the protective film has a thickness ranging from 80 μm to 150 μm.

[0106] In this way, it can be reliably ensured that the protective film is flexible and bendable enough to fully conform to the contour of a protrusion formed on one side of the substrate (if such a protrusion exists), while at the same time having sufficient thickness to reliably and effectively protect the substrate during substrate processing.

[0107] The buffer layer can be attached to the back surface of the protective film. The front surface of the buffer layer can be attached to the back surface of the protective film.

[0108] This method is particularly advantageous if a protrusion or protrusion (such as a surface irregularity or roughness, bumps, optical elements (e.g., optical lenses), other structures, etc.) protrudes, extends, or extends from one side of the substrate along the thickness direction of the substrate. In this case, the protrusion or protrusion defines the surface structure or morphology of one side of the respective substrate, thereby making that side uneven.

[0109] If a buffer layer is attached to the rear surface of the protective film, then this protrusion can be embedded in the buffer layer. Therefore, any negative impact of surface unevenness caused by the presence of the protrusion on subsequent substrate processing steps can be eliminated. In particular, the buffer layer can significantly contribute to achieving a particularly uniform and consistent distribution of pressure during processing.

[0110] By embedding the protrusions into the buffer layer, the protrusions (e.g., optical elements or other structures) can be reliably protected from any process damage during substrate processing.

[0111] There are no particular restrictions on the material of the buffer layer. In particular, the buffer layer can be formed of any type of material that allows protrusions that extend along the thickness direction of the substrate to be embedded in the buffer layer. For example, the buffer layer can be formed of resin, adhesive, or gel.

[0112] The buffer layer can be cured by external stimuli (e.g., UV radiation, heat, electric fields, and / or chemical agents). In this case, the buffer layer hardens at least to some extent when the external stimulus is applied to it. For example, the buffer layer can be formed from a curable resin, a curable adhesive, a curable gel, etc.

[0113] The buffer layer can be configured to exhibit a degree of compressibility, elasticity, and / or flexibility after curing; that is, to be compressible, elastic, and / or flexible after curing. For example, the buffer layer can be configured to become rubbery upon curing. Alternatively, the buffer layer can be configured to reach a rigid state after curing.

[0114] Preferred embodiments of the UV-curable resins used as buffer layers in the method of the present invention are ResiFlat from DISCO and TEMPLOC from DENKA.

[0115] The method may also include applying an external stimulus to the buffer layer to cure it, particularly before processing the substrate. In this way, the protection of the substrate and the processing accuracy during processing can be further improved.

[0116] The buffer layer can withstand temperatures up to 180°C or higher, preferably up to 220°C or higher, more preferably up to 250°C or higher, and even more preferably up to 300°C or higher.

[0117] The buffer layer may have a thickness ranging from 10 μm to 300 μm, preferably from 20 μm to 250 μm, and more preferably from 50 μm to 200 μm.

[0118] Before applying the protective film to one side of the substrate, a buffer layer can be attached to the rear surface of the protective film. In this case, the protective film and the buffer layer can be laminated first to form a protective sheet comprising the buffer layer and the protective film attached to the buffer layer. The protective sheet formed in this way can then be applied to one side of the substrate, for example, such that protrusions or protrusions extending from the plane of the substrate are covered by the protective film and embedded in the protective film and the buffer layer. The protective sheet can be applied such that the rear surface of the buffer layer, opposite to its front surface, is substantially parallel to the side of the substrate opposite to that side. When the protective sheet is applied to one side of the substrate, the front surface of the protective film is applied to one side of the substrate.

[0119] In this way, substrate processing methods can be performed in a particularly simple and efficient manner. For example, protective sheets can be prepared in advance, stored for later use, and used for substrate processing when needed. Therefore, protective sheets can be manufactured in large quantities, making their production particularly efficient in terms of both time and cost.

[0120] After the protective film is applied to one side of the substrate, a buffer layer can be attached to the back surface of the protective film.

[0121] In this case, a protective film is first applied to one side of the substrate, and then the side of the substrate with the protective film applied thereto is attached to the front surface of the buffer layer, for example, such that protrusions or protrusions extending from the plane of the substrate are embedded in the protective film and the buffer layer, and the rear surface of the buffer layer is substantially parallel to the side of the substrate opposite to one of the sides. This method allows the protective film to be attached to the first side of the substrate with particularly high precision, especially where there are protrusions or protrusions extending relative to the plane of the substrate.

[0122] A buffer layer may be attached to the back surface of the protective film before, and / or during, and / or after the protective film is attached to one side of the substrate.

[0123] The base sheet can be attached to the rear surface of the buffer layer. The front surface of the base sheet can be attached to the rear surface of the buffer layer.

[0124] There are no particular restrictions on the material of the substrate. The substrate can be made of soft or flexible materials, such as polymer materials (e.g., polyvinyl chloride (PVC), ethylene vinyl acetate (EVA), or polyolefins).

[0125] Alternatively, the substrate can be made of rigid or hard materials, such as polyethylene terephthalate (PET), and / or silicone, and / or glass, and / or stainless steel (SUS).

[0126] For example, if the substrate is made of polyethylene terephthalate (PET) or glass, and the buffer layer can be cured by external stimulation, then the buffer layer can be cured using radiation (e.g., UV radiation) that can penetrate polyethylene terephthalate (PET) or glass. If the substrate is made of silicon or stainless steel (SUS), then a cost-effective substrate is provided.

[0127] Furthermore, the substrate can be formed from a combination of the materials listed above.

[0128] The substrate can withstand temperatures up to 180°C or higher, preferably up to 220°C or higher, more preferably up to 250°C or higher, and even more preferably up to 300°C or higher.

[0129] The substrate may have a thickness ranging from 30 μm to 1500 μm, preferably from 40 μm to 1200 μm, and more preferably from 50 μm to 1000 μm.

[0130] The buffer layer and substrate can be attached to the back surface of the protective film before or after the protective film is applied to one side of the substrate. Specifically, the protective film, buffer layer, and substrate can be laminated first to form a protective sheet comprising the substrate, buffer layer, and a protective film attached to the buffer layer. The protective sheet formed in this manner is then applied to one side of the substrate.

[0131] The front surface of the substrate can contact the rear surface of the buffer layer, and the rear surface of the substrate opposite to its front surface can be approximately parallel to a side opposite to one side of the substrate. Therefore, when processing the side of the substrate opposite to one side, for example by placing the rear surface of the substrate on a chuck stage, appropriate counter-pressure can be applied to the rear surface of the substrate.

[0132] In this configuration, because the flat rear surface of the substrate is substantially parallel to the side of the substrate opposite to one of its sides, the pressure applied to the substrate during processing is more consistently and evenly distributed across the substrate, thereby minimizing any risk of substrate breakage. Furthermore, the flat and uniform rear surface of the substrate, aligned substantially parallel to the side of the substrate opposite to one of its sides, enables substrate processing to be performed with high precision.

[0133] Water-soluble materials may be composed of or contain water-soluble resins. In particular, water-soluble materials may be composed of or include one or more of the following: polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP).

[0134] By using water-soluble materials that are composed of or contain water-soluble resins (especially one or more of PVA, PEG, and PVP), the peel force required to remove the protective film from the substrate can be controlled in a particularly simple and reliable manner, for example by appropriately selecting the material properties of the water-soluble material, such as viscosity and / or its dilution, especially the viscosity and / or dilution of liquid water-soluble materials.

[0135] The material properties of the water-soluble material can be selected such that the adhesion between the water-soluble material coating and the protective film is greater than the adhesion between the water-soluble material coating and the substrate. In this way, the residue of the water-soluble material remaining on the substrate can be minimized after the protective film is removed from the substrate.

[0136] Water-soluble materials can be cured by external stimuli such as UV radiation, electric fields, and / or chemical agents. By curing water-soluble materials, the properties of the material can be adjusted, for example, by appropriately selecting curing conditions to reduce the peel force required to remove the protective film from the substrate. Furthermore, water-soluble materials can be configured such that they harden at least to some extent when external stimuli are applied to them.

[0137] The method may further include: curing the water-soluble material after applying a coating of water-soluble material to a protective film and / or a substrate. The water-soluble material may be cured after processing one side of the substrate and / or the side of the substrate opposite to that side.

[0138] Water-soluble materials can be substantially silicone-free or silicone-free. In this way, a particularly high substrate surface quality can be achieved on one side of the substrate after the protective film is removed from the substrate. The use of such water-soluble materials is particularly advantageous if the substrate is a semiconductor substrate (such as a semiconductor wafer).

[0139] The coating of water-soluble material applied to the protective film and / or the coating of water-soluble material applied to the substrate can have a thickness in the range of 0.5 μm to 5 μm, preferably 0.5 μm to 4 μm, more preferably 0.5 μm to 3 μm, and even more preferably 0.5 μm to 2 μm. By selecting such a coating thickness, the protective film can be conveniently removed from the substrate in a particularly effective and reliable manner, while minimizing water-soluble material residue on the substrate.

[0140] Water-soluble materials can be applied to a protective film and / or substrate in liquid form. In this way, it can be ensured particularly reliably that the desired portions of the protective film and / or the substrate to be coated are fully and uniformly coated with the water-soluble material, including protrusions and / or recesses on one side of the substrate. By applying the water-soluble material to the protective film in liquid form, a particularly complete and uniform coating can be obtained. For example, the water-soluble material can be applied to the protective film and / or substrate by spraying or spin coating. Furthermore, the water-soluble material can be applied to the protective film and / or substrate by screen printing. After the water-soluble material is applied to the protective film and / or substrate, it can be cured. In this way, the water-soluble material can harden, as detailed above. This method allows the water-soluble material to be placed or positioned particularly reliably on the protective film and / or substrate. Furthermore, the thickness of the water-soluble material can be controlled in a particularly accurate and reliable manner.

[0141] Water-soluble materials can be applied to the protective film and / or substrate in solid form. This allows for simple application of the water-soluble material. For example, the water-soluble material can be applied to the protective film and / or substrate in the form of a film or sheet (especially a thin film or sheet).

[0142] The side of the substrate opposite to one side may consist of or include the following: cutting the substrate along its thickness direction. The substrate may be cut along its entire thickness to completely divide it, or only along a portion of its thickness. If present, the substrate may be cut along one or more dividing lines. The substrate may be divided into multiple individual components. Individual components may be, for example, chips or dies.

[0143] The substrate can be cut along its thickness direction and may consist of or include the following: mechanically cut substrate; and / or laser-cut substrate; and / or plasma-cut substrate. For example, the substrate can be mechanically cut by blade dicing or sawing.

[0144] The substrate can be cut in a single mechanical cutting step, a single laser cutting step, or a single plasma cutting step. Alternatively, the substrate can be cut by a series of mechanical cutting and / or laser cutting and / or plasma cutting steps.

[0145] Laser cutting can be performed, for example, by ablation laser cutting and / or by stealth laser cutting, i.e., by forming a modified area within a substrate by applying a laser beam, as will be further detailed below, and / or by forming multiple hole areas in the substrate by applying a laser beam. Each of these hole areas may consist of a modified area and a space within the modified area that opens to the substrate surface.

[0146] In stealth laser cutting, a laser beam with a wavelength that allows the laser beam to penetrate through the substrate is applied to the substrate. Therefore, the substrate is made of a material transparent to the laser beam. The laser beam is applied to the substrate at at least multiple locations to form multiple modified regions within the substrate (e.g., within or inside a large portion of the substrate). Specifically, the laser beam may be applied to the substrate along at least one dividing line at at least multiple locations to form multiple modified regions within the substrate along at least one dividing line.

[0147] The laser beam can be a pulsed laser beam. A pulsed laser beam can have a pulse width, for example, in the range of 1 fs to 1000 ns.

[0148] The modified region is a substrate region that has been modified by applying a laser beam. The modified region can be a substrate region where the structure of the substrate material has been modified. The modified region can be a substrate region where the substrate has been damaged. The modified region can include amorphous regions or cracked regions, or it can be an amorphous region or a cracked region.

[0149] By forming these modified regions, the strength of the substrate in the regions where the modified regions are formed is reduced. Therefore, the slicing of substrates with multiple modified regions already formed (e.g., along at least one slitting line) is greatly facilitated.

[0150] For example, if a crack in the substrate extends from the modified region to one side of the substrate and the side opposite to that side, the substrate can be completely separated in a stealth laser cutting process. If the substrate is not completely separated in a stealth laser cutting process, the method may further include: completely separating the substrate, for example by applying an external force to the substrate.

[0151] The side of the substrate opposite to one side may include or be constituted by: thinning the substrate to reduce its thickness. Thinning the substrate may be constituted or include: grinding the substrate from the side opposite to one side, and / or polishing the substrate from the side opposite to one side, and / or etching the substrate from the side opposite to one side.

[0152] One side of the substrate can be processed by means of a protective film, for example, by using a stealth laser cutting process. In this process, a laser beam is applied to the substrate through the protective film. In this case, the wavelength of the laser beam is selected such that the laser beam transmits through the protective film, that is, the protective film is transparent to the laser beam.

[0153] For example, if a crack in the substrate extends from the modified region to one side of the substrate and the side opposite to that side, the substrate can be completely separated in a stealth laser cutting process. If the substrate is not completely separated in a stealth laser cutting process, the method may further include, for example, completely separating the substrate by applying an external force to the substrate.

[0154] The method further includes removing the protective film from the substrate after processing one side of the substrate and / or the side of the substrate opposite to that one side. The removal of the protective film from the substrate is significantly facilitated by providing a coating of water-soluble material between the protective film and the substrate, at least in the central region or portion thereof, as detailed above. In particular, the water-soluble material can reduce the peeling force required to peel off the protective film. Therefore, the risk of any damage to the substrate caused by the device during the removal of the protective film from the substrate is further reduced. Furthermore, the presence of the water-soluble material minimizes the risk of any residue of the protective film material remaining on the substrate after removal.

[0155] The method may further include: removing the protective film and buffer layer from the substrate. The protective film and buffer layer can be removed from the substrate after processing one side of the substrate and / or the side of the substrate opposite to that one side.

[0156] The buffer layer and the protective film can be removed separately (i.e., one after the other). For example, the buffer layer can be removed first, followed by the protective film. Alternatively, the buffer layer and the protective film can be removed together.

[0157] The method may further include removing a protective film, a buffer layer, and a substrate from the substrate. The protective film, buffer layer, and substrate can be removed from the substrate after processing one side of the substrate and / or the side of the substrate opposite to that one side.

[0158] The substrate, buffer layer, and protective film can be removed individually (i.e., one after another). For example, the substrate can be removed first, followed by the buffer layer, and then the protective film. Alternatively, the substrate and buffer layer can be removed, followed by the protective film. Or, the substrate, buffer layer, and protective film can be removed together.

[0159] The method may further include cleaning one side of the substrate after removing the protective film from the substrate, specifically, cleaning one side of the substrate with water. If water-soluble material residue remains on the substrate after removing the protective film, due to the water-soluble nature of the material, these residues can be removed simply, reliably, and effectively by cleaning one side of the substrate (especially by cleaning one side of the substrate with water). Therefore, a substrate surface free of any residue or other types of contaminants can be obtained on one side of the substrate. For example, one side of the substrate can be cleaned with deionized water. Attached Figure Description

[0160] In the following explanation, non-limiting embodiments of the invention are described with reference to the accompanying drawings, in which:

[0161] Figure 1 A perspective view of a wafer that serves as a substrate to be processed by the method of the present invention is shown.

[0162] Figure 2 A cross-sectional view illustrating the step of applying a protective film to one side of a wafer in a method according to a first embodiment of the invention;

[0163] Figure 3 A cross-sectional view illustrating the effect of the step of attaching a protective film to one side of a wafer in the method according to the first embodiment;

[0164] Figure 4 A cross-sectional view showing the step of applying a protective film to one side of a wafer in a modified method according to a first embodiment of the invention;

[0165] Figure 5 A cross-sectional view illustrating the effect of the step of attaching a protective film to one side of a wafer in the modified method according to the first embodiment;

[0166] Figure 6 A cross-sectional view illustrating the effect of the step of applying a water-soluble material coating to a wafer in the method according to a second embodiment of the invention;

[0167] Figure 7 A cross-sectional view is shown illustrating the step of cutting the mount tape attached to the wafer in the method according to a second embodiment of the invention;

[0168] Figure 8 A cross-sectional view illustrating the effect of the step of attaching a protective film to one side of a wafer in the method according to the second embodiment;

[0169] Figure 9 A cross-sectional view illustrating the steps of cutting the protective film, buffer layer, and substrate attached to the wafer in a method according to a third embodiment of the present invention;

[0170] Figure 10 To show Figure 9 A cross-sectional view showing the effect of the steps illustrated. Detailed Implementation

[0171] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. The preferred embodiments relate to a method of processing a substrate.

[0172] In the first to third embodiments, the processing method of the present invention is performed on the wafer 2, which serves as a substrate (see...). Figure 1 Wafer 2 can be, for example, a MEMS wafer having MEMS devices formed on one of its side surfaces 4 (i.e., the front surface). However, wafer 2 is not limited to a MEMS wafer, but can also be a CMOS wafer having CMOS devices (preferably as solid-state imaging devices) formed on its front surface 4, or a wafer having other types of devices on its front surface 4.

[0173] Wafer 2 can be made of semiconductor (e.g., silicon (Si)). This silicon wafer 2 can include devices such as integrated circuits (ICs) and large-scale integration (LSIs) on a silicon substrate. Alternatively, wafer 2 can be an optical device wafer configured to form optical devices such as LEDs (light-emitting diodes) on an inorganic material substrate, such as ceramic, glass, or sapphire. Wafer 2 is not limited to these and can be formed in any other manner. Furthermore, combinations of the exemplary wafer designs described above are also possible.

[0174] Wafer 2 can have a thickness in the micrometer range, preferably in the range of 30 μm to 1000 μm.

[0175] Wafer 2 is preferably circular. However, there are no particular limitations on the shape of wafer 2. In other embodiments, wafer 2 may be, for example, oval, elliptical, or polygonal (e.g., rectangular or square).

[0176] Wafer 2 has multiple intersecting dividing lines 6 formed on its front side 4 (see...) Figure 1 (also called a street), thereby dividing the wafer 2 into multiple rectangular regions for forming devices 8 (such as those previously described). These devices 8 are formed in device regions 10 of the wafer 2. In the case of a circular wafer 2, the device regions 10 are preferably generally circular and arranged concentrically with the outer circumference of the wafer 2.

[0177] The device region 10 of wafer 2 may have a plurality of protrusions 11 projecting from the flat surface of wafer 2 (see [reference]). Figure 2 The protrusion 11 can be, for example, a bump used to establish electrical contact with the device 8 in the device region 10. The height of the protrusion 11 in the thickness direction of the wafer 2 can be in the range of 20 μm to 500 μm.

[0178] As in Figure 1 As schematically shown, device region 10 is surrounded by an annular peripheral edge region 12. No device is formed within this peripheral edge region 12. The peripheral edge region 12 is preferably arranged concentrically with the outer circumference of device region 10 and / or wafer 2. The radial extension of the peripheral edge region 12 can be in the range of millimeters (mm), and preferably in the range of 1 mm to 3 mm.

[0179] Wafer 2 also has a side 14 (i.e., the back surface) opposite to the front side 4 (see...). Figure 1 ).

[0180] In the following text, reference will be made to Figures 1 to 5 A first embodiment of the present invention is described.

[0181] A protective film 16 is provided having a front surface 18 and a rear surface 20 opposite to the front surface 18 (see...). Figure 2 ).

[0182] The protective film 16 can be made of a plastic material (e.g., a polymer). For example, the protective film 16 can be made of a polyolefin (such as polyethylene (PE), polypropylene (PP), or polybutene (PB)). The protective film 16 can have a thickness ranging from 5 μm to 500 μm, preferably from 5 μm to 200 μm, more preferably from 8 μm to 100 μm, even more preferably from 10 μm to 80 μm, and even more preferably from 12 to 50 μm. In this embodiment, the protective film 16 has a generally circular shape in its top view, and the outer diameter of the protective film is approximately the same as the outer diameter of the wafer 2. In other embodiments, the outer diameter of the protective film 16 can be smaller (e.g., slightly smaller) or larger (e.g., slightly larger) than the outer diameter of the wafer 2. For example, the outer diameter of the protective film 16 can be smaller than the outer diameter of the wafer 2, but approximately the same as or larger than the outer diameter of the device region 10 of the wafer 2.

[0183] The coating of water-soluble material 22 can be applied to the entire front surface 18 of the protective film 16 (see...). Figure 2 The water-soluble material 22 may be composed of or include a water-soluble resin, such as PVA, PEG, and / or PVP. The coating of the water-soluble material may have a thickness ranging from 0.5 μm to 5 μm, preferably from 0.5 μm to 4 μm, more preferably from 0.5 μm to 3 μm, and even more preferably from 0.5 μm to 2 μm. In this embodiment, the water-soluble material 22 is applied to the protective film 16 in liquid form, for example by spraying, spin coating, or screen printing.

[0184] For example, the coating of water-soluble material 22 can be applied to the front surface 18 of the protective film 16 shortly before (e.g. immediately) applying the protective film 16 to the front side 4 of the wafer 2, or, for example, during or shortly after the manufacture of the protective film 16.

[0185] After applying the coating of water-soluble material 22 to the protective film 16, the protective film 16 is applied to the front side 4 of the wafer 2, such as... Figure 2 As indicated by the arrows in the diagram. The front surface 18 of the protective film 16 faces the front side 4 of the wafer 2, and the protective film 16 is applied to the wafer 2 such that there is no adhesive between the entire front surface 18 of the protective film 16 and the entire front side 4 of the wafer 2. The entire front surface 18 of the protective film 16 is free of adhesive. Therefore, in the entire area where the protective film 16 and the wafer 2 are in contact, only water-soluble material 22 is present between the protective film 16 and the wafer 2. The protective film 16 is applied to the front side 4 of the wafer 2 to cover the device 8 formed in the device region 10, thereby protecting the device 8 from, for example, contamination and damage.

[0186] After applying the protective film 16 to the front side 4 of wafer 2, an external stimulus is applied to the protective film 16, causing the protective film 16 to attach to the front side 4 of wafer 2. The result of this attachment step is as follows: Figure 3 As shown in the image.

[0187] Applying external stimulation to the protective film 16 can be constituted or included by: heating the protective film 16, and / or cooling the protective film 16, and / or applying pressure to the protective film 16, and / or applying a vacuum to the protective film 16, and / or irradiating the protective film 16, for example, by using a laser beam with radiation (such as light or UV radiation). Specifically, in this embodiment, applying external stimulation to the protective film 16 can be constituted or included by heating the protective film 16. Adhesion is created between the protective film 16 and the wafer 2 through a heating process. The protective film 16, when heated, can be bendable, elastic, flexible, stretchable, soft, and / or compressible. In this way, it can be reliably ensured that the protective film 16 conforms to the wafer surface on the front side 4 of the wafer 2, for example, by causing the protective film to adhere to the shape of the wafer and follow the contour of the protrusion 11 (see...). Figure 3 The protrusion 11 can be at least partially embedded in the protective film 16.

[0188] After the protective film 16 is attached to the front side 4 of the wafer 2, the front side 4 and / or the rear side 14 of the wafer 2 are processed while the protective film 16 is attached to the wafer 2. Therefore, during the processing of the wafer 2, the wafer 2 (especially the device 8 formed in the device region 10) is reliably protected from, for example, contamination and damage.

[0189] The back side 14 of the wafer 2 may include or be constituted by, for example, cutting the wafer 2 from the back side 14 along the cleaving line 6 (see...). Figure 1 For example, wafer 2 can be cut along the entire thickness of the substrate to completely separate wafer 2, or wafer 2 can be cut only along a portion of the substrate thickness. Wafer 2 can be completely divided by cutting along the cleaving line 6 to obtain multiple individual components (e.g., chips or dies). Each chip or die thus obtained may include one or more devices 8.

[0190] The wafer 2 cut from the rear side 14 may consist of or include the following: mechanically cut wafer 2, and / or laser cut wafer 2, and / or plasma cut wafer 2, as detailed above.

[0191] Processing the back side 14 of wafer 2 may include or be constituted by: thinning wafer 2 in order to reduce the thickness of wafer 2. Thinning wafer 2 may be constituted or include: grinding wafer 2 from back side 14, and / or polishing wafer 2 from back side 14, and / or etching wafer 2 from back side 14, as detailed above.

[0192] The front side 4 of the wafer 2 can be formed by processing a protective film 16, for example, by using a stealth laser cutting process. In this process, a laser beam is applied to the wafer 2 through the protective film 16, as detailed above.

[0193] After processing the front side 4 and / or the rear side 14 of wafer 2, the protective film 16 is removed from wafer 2. Because the water-soluble material 22 is present between the protective film 16 and wafer 2 in the entire area where the protective film 16 contacts each other, the removal of the protective film 16 from wafer 2 is significantly facilitated. In particular, the water-soluble material 22 reduces the peeling force required to peel the protective film 16 from wafer 2. Therefore, the risk of any damage to wafer 2 during the process of removing the protective film 16 is further reduced. Furthermore, the presence of the water-soluble material 22 minimizes the risk of any residue of the protective film material remaining on wafer 2 after the removal of the protective film 16.

[0194] After removing the protective film 16 from wafer 2, the front side 4 of wafer 2 can be cleaned with water (e.g., deionized water). If, after removing the protective film, residues of the water-soluble material 22 remain on wafer 2, for example due to the presence of protrusions 11, these residues can be removed simply, reliably, and effectively by cleaning the front side 4 with water due to the water-soluble nature of the material 22. Therefore, a wafer surface free of any residues or other types of contaminants can be obtained on the front side 4 of wafer 2.

[0195] Figure 4 The step of applying the protective film 16 to the front surface 4 of the wafer 2 in the modified method according to the first embodiment is shown. This modified method differs from the method of the first embodiment in that: the outer diameter of the protective film 16 is larger than the outer diameter of the wafer 2; the coating of the water-soluble material 22 is applied only to the central region of the front surface 18 of the protective film 16; and the protective film 16 is provided with an adhesive layer 24 existing only in the peripheral region of the front surface 18 of the protective film 16 (see [link to original text]). Figure 4 ).

[0196] like Figure 4As further shown, the outer peripheral portion of the protective film 16 is attached to the annular frame 26. Specifically, the outer peripheral portion of the protective film 16 is attached to the annular frame 26 such that the protective film 16 closes the central opening of the annular frame 26, i.e., the region within the inner diameter of the annular frame 26. In this embodiment, the step of attaching the outer peripheral portion of the protective film 16 to the annular frame 26 is performed before attaching the protective film 16 to the wafer 2. In this way, the processing of the protective film 16 is facilitated, particularly when the protective film 16 is applied and attached to the wafer 2. Furthermore, after the protective film 16 is attached to the wafer 2, the wafer 2 can be held by the annular frame 26 through the protective film 16. Thus, a wafer cell comprising the wafer 2, the protective film 16, and the annular frame 26 is formed, facilitating the processing, handling, and transport of the wafer 2.

[0197] The protective film 16 can be attached to the annular frame 26 by an adhesive (e.g., through a portion of the adhesive layer 24), as will be detailed below. Alternatively, the protective film 16 can be attached to the annular frame 26 by applying an external stimulus to it. In this case, no adhesive may be present between the protective film 16 and the annular frame 26. Applying an external stimulus to the protective film 16 can consist of or include: heating the protective film 16, and / or cooling the protective film 16, and / or applying pressure to the protective film 16, and / or applying a vacuum to the protective film 16, and / or irradiating the protective film 16 with radiation (such as light or UV radiation) using a laser beam. In particular, applying an external stimulus to the protective film 16 can consist of or include heating the protective film 16. Adhesion is generated between the protective film 16 and the annular frame 26 through the heating process.

[0198] The central region of the front surface 18 of the protective film 16 corresponds to and substantially coincides with the device region 10 of the wafer 2. A water-soluble material 22 is applied to the protective film 16. The peripheral region of the front surface 18 of the protective film 16, to which the adhesive layer 24 is disposed, surrounds the central region of the front surface 18 of the protective film 16. The peripheral region of the front surface 18 of the protective film 16, to which the adhesive layer 24 is disposed, corresponds to and substantially coincides with the peripheral outer region 12 of the wafer 2. The adhesive layer 24 has a generally annular shape. The protective film 16 is applied to the front side 4 of the wafer 2 (e.g., ...). Figure 4 (As indicated by the arrow in the diagram), so that the adhesive layer 24 only contacts the peripheral edge region 12 of the wafer 2. Only water-soluble material 22 exists between the central region of the front surface 18 of the protective film 16 and the device region 10 of the wafer 2.

[0199] Figure 4The illustrated embodiment can be further modified in various ways. Specifically, the adhesive layer 24 can be disposed over the entire outer (i.e., radially outer) region of the front surface 18 of the protective film 16, in the central region of the front surface 18. In this case, the adhesive layer 24 extends from the outer circumferential edge of the central region of the front surface 18 of the protective film 16 to the outer circumferential edge of the protective film 16. Alternatively, for example, the adhesive layer 24 can be disposed only over the peripheral edge region 12 of the front surface 18 of the protective film 16 and the wafer 2 (see...). Figure 4 and 5 In those areas that contact the annular frame 26.

[0200] exist Figure 4 In the illustrated embodiment, the water-soluble material 22 is applied only to the central region of the front surface 18 of the protective film 16. The water-soluble material 22 thus extends (i.e., radially) to the inner circumferential edge of the adhesive layer 24. The water-soluble material 22 is absent outside the inner circumferential edge of the adhesive layer 24 (i.e., radially outward). This arrangement can be particularly reliably achieved, for example, by using a mask to cover the area of ​​the front surface 18 of the protective film 16 outside the inner circumferential edge of the adhesive layer 24 (i.e., the area outside the central region of the front surface 18 of the protective film 16). The water-soluble material 22 can be applied to the front surface 18 of the protective film 16, for example, by screen printing or spraying.

[0201] Alternatively, for example, the water-soluble material 22 can be applied to the entire front surface 18 of the protective film 16. The water-soluble material 22 can be applied to the entire portion of the front surface 18 of the protective film, which is in contact with the front side 4 of the wafer 2. In those areas of the front surface 18 of the protective film 16 where the adhesive layer 24 is present, the water-soluble material 22 can be disposed on top of the adhesive layer 24 (i.e., on the side of the adhesive layer 24 opposite to the side of the adhesive layer 24 that is in contact with the protective film 16).

[0202] After applying the protective film 16 to the front side 4 of the wafer 2, an external stimulus is applied to the protective film 16, causing the protective film 16 to attach to the front side 4 of the wafer 2. The result of this attachment step is as follows: Figure 5 As shown in the image.

[0203] External stimulation is applied to the protective film 16 in the same manner as detailed above for the method according to the first embodiment, thereby attaching the central region of the front surface 18 of the protective film 16 to the device region 10 of the wafer 2. Further, the peripheral region of the front surface 18 of the protective film 16 is attached to the peripheral edge region 12 of the wafer 2 via an adhesive layer 24. The adhesion between the protective film 16 and the wafer 2 is further improved by providing the adhesive layer 24. Since the adhesive layer 24 exists only in the peripheral region of the front surface 18 of the protective film 16, the area where the protective film 16 and the wafer 2 are attached to each other via the adhesive layer 24 is significantly reduced compared to the case where the adhesive layer is provided on the entire front surface 18 of the protective film 16. Therefore, the protective film 16 can be more easily separated from the wafer 2, and the risk of damage to the wafer 2 is greatly reduced. Furthermore, since the adhesive layer 24 only contacts the peripheral edge region 12 of the wafer 2 where no device is formed, contamination of the device 8 in the device region 10 by adhesive residue is reliably prevented.

[0204] The adhesive of adhesive layer 24 can be cured by external stimuli (such as heat, UV radiation, electric fields, and / or chemical agents). In this way, the protective film 16 can be removed from the wafer 2 particularly easily after processing. External stimuli can be applied to the adhesive to reduce its adhesive strength, thereby allowing the protective film 16 to be removed particularly easily.

[0205] After attaching the protective film 16 to the front side 4 of the wafer 2, the following steps can be performed in the same manner as detailed above for the method according to the first embodiment: processing the front side 4 and / or the rear side 14 of the wafer 2, removing the protective film 16 from the wafer 2, and cleaning the front side 4 of the wafer 2 with water (e.g., deionized water).

[0206] Because a water-soluble material 22 exists between the central region of the front surface 18 of the protective film 16 and the device region 10 of the wafer 2, the protective film 16 can be easily removed from the wafer 2. In particular, the water-soluble material 22 reduces the peeling force required to peel the protective film 16 from the wafer 2. Therefore, the risk of any damage to the wafer 2 during the process of removing the protective film 16 from the wafer (particularly in the device region 10) is further reduced. Furthermore, the presence of the water-soluble material 22 minimizes the risk of any residue of the protective film material remaining on the wafer 2 (particularly in the device region 10) after the removal of the protective film 16. As described above, the process of removing the protective film 16 from the wafer 2 can be further facilitated by applying an external stimulus to cure the adhesive of the adhesive layer 24.

[0207] In the following text, reference will be made to Figures 6 to 8 A second embodiment of the present invention is described.

[0208] The method according to the second embodiment differs from the method according to the first embodiment in that the coating of water-soluble material 22 is applied to the front side 4 of wafer 2 instead of the front surface 18 of protective film 16, and the outer diameter of protective film 16 is larger than the outer diameter of wafer 2. Further, the method of the second embodiment includes the optional step of attaching wafer 2 to mounting tape 28 (see [link to documentation]). Figure 6 The remaining steps of the method in the first embodiment are performed in the same manner as the method in the second embodiment. Therefore, a detailed description of its repetition is omitted.

[0209] Specifically, optionally, in the method of the second embodiment, the rear side 14 of wafer 2 is attached to the mounting tape 28, for example, by an adhesive. The adhesive may be present on the entire surface of the mounting tape 28 that contacts the rear side 14 of wafer 2, or only in a peripheral region of this surface. Alternatively, no adhesive may be present between the mounting tape 28 and the rear side 14 of wafer 2. In this case, the mounting tape 28 can be attached to the rear side 14 of wafer 2 by applying an external stimulus (e.g., the external stimulus detailed above) to the mounting tape 28.

[0210] like Figure 6 As further shown, the outer peripheral portion of the mounting band 28 is attached to the annular frame 30. Specifically, the outer peripheral portion of the mounting band 28 is attached to the annular frame 30 such that the mounting band 28 closes the central opening of the annular frame 30 (i.e., the area within the inner diameter of the annular frame 30). In this embodiment, the step of attaching the outer peripheral portion of the mounting band 28 to the annular frame 30 is performed before applying the coating of the water-soluble material 22 to the front side 4 of the wafer 2. In this way, the processing of the wafer 2 is facilitated, particularly when the coating of the water-soluble material 22 is applied to the wafer.

[0211] After attaching the mounting tape 28 to the rear side 14 of the wafer 2, a coating of water-soluble material 22 is applied to the entire front side 4 of the wafer 2. The result of this application step is... Figure 6 As shown in the figure, the coating of water-soluble material 22 covers the entire front side 4 of the wafer 2, including the surface of the protrusion 11. The coating of water-soluble material 22 applied to the front side 4 of the wafer 2 can have a thickness in the range of 0.5 μm to 5 μm, preferably 0.5 μm to 4 μm, more preferably 0.5 μm to 3 μm, and even more preferably 0.5 μm to 2 μm.

[0212] The water-soluble material 22 applied to the front side 4 of wafer 2 is the same as the water-soluble material in the method described above for the first embodiment. In particular, the water-soluble material 22 may be composed of or include water-soluble resins (such as PVA, PEG and / or PVP).

[0213] In this embodiment, the water-soluble material 22 is applied in liquid form to the front side 4 of the wafer 2 by, for example, spraying, spin coating, or screen printing. During this application process, the support or carrier on which the wafer 2 can be held (such as a chuck stage) is protected from contamination by the liquid water-soluble material 22 due to the presence of the mounting strip 28.

[0214] After applying the water-soluble material 22 coating to the front side 4 of the wafer 2, an optional step is performed, such as cutting the mounting tape 28 along the outer circumference of the wafer 2 using a cutting blade, as... Figure 7 As shown by the dashed lines in the diagram. Mounting strip 28 is cut such that its outer diameter is substantially the same as the outer diameter of wafer 2 (see [reference]). Figure 7 and 8 This dicing step facilitates the subsequent application of the protective film 16 onto wafer 2, especially since the protective film 16 is also held by the annular frame (i.e., the annular frame 26) (see...). Figure 8 ).

[0215] As an alternative step, instead of cutting the mounting tape 28, the mounting tape 28 can be removed from the wafer 2 after the coating of the water-soluble material 22 is applied to the front side 4 of the wafer 2 and before the protective film 16 is applied to the wafer 2.

[0216] Following the optional steps of cutting or removing the mounting tape 28 from wafer 2, a protective film 16 is applied and attached to the front side 4 of wafer 2. The results of these steps are... Figure 8 As shown in the image.

[0217] The steps of applying and attaching the protective film 16 to the wafer 2 are performed in the same manner as detailed above for the method of the first embodiment. The outer peripheral portion of the protective film 16 is attached to the annular frame 26 in the same manner as the method of the variation of the first embodiment.

[0218] Specifically, when the protective film 16 is applied to the wafer 2, the front surface 18 of the protective film 16 faces the front side 4 of the wafer 2, and the protective film 16 is applied to the wafer 2 such that there is no adhesive between the entire front surface 18 of the protective film 16 and the entire front side 4 of the wafer 2. The entire front surface 18 of the protective film 16 is free of adhesive. Therefore, in the entire area where the protective film 16 and the wafer 2 are in contact, only water-soluble material 22 is present between the protective film 16 and the wafer 2. The protective film 16 is applied to the front side 4 of the wafer 2 to cover the device 8 formed in the device region 10, thereby protecting the device 8 from, for example, contamination and damage.

[0219] After the protective film 16 is applied to the front side 4 of the wafer 2, an external stimulus is applied to the protective film 16, causing the protective film 16 to attach to the front side 4 of the wafer 2. The external stimulus is applied to the protective film 16 in the same manner as detailed above for the method of the first embodiment.

[0220] After attaching the protective film 16 to the front side 4 of the wafer 2, the following steps can be performed in the same manner as detailed above for the method according to the first embodiment: processing the front side 4 and / or the rear side 14 of the wafer 2, removing the protective film 16 from the wafer 2, and cleaning the front side 4 of the wafer 2 with water (e.g., deionized water).

[0221] In the modification method according to the second embodiment, a protective film 16 with an outer diameter substantially the same as the outer diameter of wafer 2 (see [reference]). Figure 2 and 3 This modification method differs substantially from the method according to the first embodiment only in that the coating of water-soluble material 22 is applied to the front side 4 of wafer 2 instead of the front surface 18 of protective film 16.

[0222] In other embodiments, the coating of water-soluble material 22 can be applied to the front side 4 of wafer 2, and the coating of water-soluble material 22 can be applied to the front surface 18 of protective film 16.

[0223] Furthermore, in the same manner as detailed above for the modification method according to the first embodiment, the protective film 16 may be provided with an adhesive layer 24 existing only in the peripheral region of the front surface 18 of the protective film 16 (see...). Figure 4 Furthermore, the arrangement of the adhesive layer 24 and / or the arrangement of the water-soluble material 22 can be modified, for example, in the manner detailed above with respect to the modification of the first embodiment.

[0224] In the following text, reference will be made to Figure 9 and Figure 10 A third embodiment of the present invention is described.

[0225] The method according to the third embodiment differs from the method according to the second embodiment in that: the buffer layer 32 and the substrate 34 are attached to the rear surface 20 of the protective film 16 (see...). Figure 9 and 10 Further, the optional step of cutting the protective film 16, buffer layer 32, and substrate 34 attached to wafer 2 is performed. The remaining steps of the method of the second embodiment are performed in the same manner as the method of the third embodiment. Therefore, a detailed description of its repetition is omitted.

[0226] Specifically, in the method of the third embodiment, before attaching the protective film 16 to the front side 4 of the wafer 2, the buffer layer 32 and the substrate 34 may be attached to the rear surface 20 of the protective film 16. The front surface of the buffer layer 32 is attached to the rear surface 20 of the protective film 16, and the front surface of the substrate 34 is attached to the rear surface of the buffer layer 32. The rear surface of the buffer layer 32 is opposite to the front surface of the buffer layer 32. The buffer layer 32 and the substrate 34 may have the features, properties, and characteristics detailed above.

[0227] In the same manner as detailed above for the method according to the second embodiment, a protective film 16 having a buffer layer 32 and a substrate 34 attached thereto is attached to the front side 4 of the wafer 2.

[0228] When the protective film 16, having a buffer layer 32 and a substrate 34 attached thereto, is applied and attached to the front side 4 of the wafer 2, the protrusion 11 is embedded in the protective film 16 and the buffer layer 32, thus providing particularly reliable protection against any damage during wafer processing, as detailed above.

[0229] After attaching the protective film 16, which has a buffer layer 32 and a substrate 34 attached thereto, to the front side 4 of the wafer 2, an optional step is performed, for example, by using a dicing blade, to cut the protective film 16, the buffer layer 32, and the substrate 34 along the outer circumference of the wafer 2. Figure 9 The arrows and dashed lines in the diagram indicate the result of this cutting step. Figure 10 As shown in the figure. The protective film 16, the buffer layer 32, and the substrate 34 are cut such that each of them has an outer diameter approximately the same as the outer diameter of wafer 2 (see Figure 2). Figure 9 and 10 This dicing step can facilitate subsequent processing of wafer 2, especially when processing the front side 4 and / or the back side 14 of wafer 2.

[0230] After the optional steps of cutting the protective film 16, the buffer layer 32 and the substrate 34, the following steps can be performed in the same manner as detailed above for the methods according to the first and second embodiments: processing the front side 4 and / or the back side 14 of the wafer 2, removing the protective film 16 from the wafer 2, and cleaning the front side 4 of the wafer 2 with water (e.g., deionized water).

[0231] The substrate 34, buffer layer 32, and protective film 16 can be removed from wafer 2 individually (i.e., one after another). For example, the substrate 34 can be removed first, followed by the buffer layer 32, and then the protective film 16. Similarly, the substrate 34 and buffer layer 32 can be removed together, followed by the protective film 16. Alternatively, the substrate 34, buffer layer 32, and protective film 16 can be removed together.

[0232] According to the method of the third embodiment, modification can be achieved by applying the coating of water-soluble material 22 to the front surface 18 of the protective film 16 instead of the front side 4 of the wafer 2. Alternatively, the coating of water-soluble material 22 can be applied to the front side 4 of the wafer 2, and the coating of water-soluble material 22 can be applied to the front surface 18 of the protective film 16.

[0233] Furthermore, in the same manner as detailed above for the modification method according to the first embodiment, the protective film 16 may be provided with an adhesive layer 24 existing only in the peripheral region of the front surface 18 of the protective film 16 (see...). Figure 4 Furthermore, the arrangement of the adhesive layer 24 and / or the arrangement of the water-soluble material 22 can be modified, for example, in a manner detailed above with respect to the modification method of the first embodiment.

[0234] In the methods according to the first to third embodiments described above, the protective film 16 is applied and attached to the front side 4 of the substrate (i.e., the wafer 2). However, in other embodiments of the invention, the protective film may be applied and attached to the rear side of the substrate.

Claims

1. A method for processing a substrate (2), said substrate having a side surface (4) and a side surface (14) opposite to said side surface (4), wherein, The method includes: A protective film (16) is provided, the protective film having a front surface (18) and a rear surface (20) opposite to the front surface (18). Applying a coating of water-soluble material (22) to at least the central region of the front surface (18) of the protective film (16), and / or applying a coating of water-soluble material (22) to at least the central portion of one side (4) of the substrate (2); After the coating is applied to the protective film (16) and / or the coating is applied to the substrate (2), the protective film (16) is applied to one side (4) of the substrate (2), wherein the front surface (18) of the protective film (16) faces the one side (4) of the substrate (2) and the protective film (16) is applied such that there is no adhesive between at least the central region of the front surface (18) of the protective film (16) and the one side (4) of the substrate (2); During and / or after applying the protective film (16) to one side (4) of the substrate (2), an external stimulus is applied to the protective film (16) to cause the protective film (16) to attach to the one side (4) of the substrate (2); and Process the one side (4) of the substrate (2) and / or the side (14) of the substrate (2) opposite to the one side (4). The adhesion between the coating of the water-soluble material (22) and the protective film (16) is greater than the adhesion between the coating of the water-soluble material (22) and the substrate (2).

2. A method for processing a substrate (2), the substrate having a side surface (4) and a side surface (14) opposite to said side surface (4), wherein, The method includes: A protective film (16) is provided, the protective film having a front surface (18) and a rear surface (20) opposite to the front surface (18), wherein the protective film (16) has a coating of a water-soluble material (22), the coating being applied to at least the central region of the front surface (18) of the protective film (16); The protective film (16) is applied to one side (4) of the substrate (2), wherein the front surface (18) of the protective film (16) faces the one side (4) of the substrate (2) and the protective film (16) is applied such that there is no adhesive between at least the central region of the front surface (18) of the protective film (16) and the one side (4) of the substrate (2). During and / or after applying the protective film (16) to one side (4) of the substrate (2), an external stimulus is applied to the protective film (16) to cause the protective film (16) to attach to the one side (4) of the substrate (2); and Process the one side (4) of the substrate (2) and / or the side (14) of the substrate (2) opposite to the one side (4). The adhesion between the coating of the water-soluble material (22) and the protective film (16) is greater than the adhesion between the coating of the water-soluble material (22) and the substrate (2).

3. The method according to claim 1 or 2, wherein, The coating applied to the protective film (16) and / or the coating applied to the substrate (2) have a thickness in the range of 0.5 to 5 μm.

4. The method according to claim 1 or 2, the method further comprising removing the protective film (16) from the substrate (2) after processing the one side (4) of the substrate (2) and / or processing the side (14) of the substrate (2) opposite to the one side (4).

5. The method according to claim 4, further comprising cleaning one side (4) of the substrate (2) with water after removing the protective film (16) from the substrate (2).

6. The method according to claim 1 or 2, wherein, The protective film (16) is provided with an adhesive layer (24). The adhesive layer (24) is disposed only in the peripheral region of the front surface (18) of the protective film (16), the peripheral region surrounding the central region of the front surface (18) of the protective film (16), and The protective film is applied to one side (4) of the substrate such that the adhesive layer (24) contacts only the peripheral portion of one side (4) of the substrate (2).

7. The method according to claim 1 or 2, wherein, Applying the external stimulus to the protective film (16) includes: heating the protective film (16), and / or cooling the protective film (16), and / or applying pressure to the protective film (16), and / or irradiating the protective film (16) with light or UV rays.

8. The method according to claim 1 or 2, wherein, The protective film (16) is formed of a polymer.

9. The method according to claim 8, wherein, The polymer is a polyolefin.

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