Methods for processing a substrate

Abstract

Method for processing a substrate (W), wherein the substrate (W) has a side (1) and a side (6) opposite the one side (1), the substrate (W) has at least one recess (7) on one side (1) or on the side (6) opposite one side (1), and The procedure includes: Provide a protective film (4); Applying the protective film (4) to the side of the substrate (W) which has the at least one recess (7), such that at least a central area of ​​a front surface (4a) of the protective film (4) is in direct contact with the side of the substrate (W) which has the at least one recess (7), so that no adhesive is present between at least the central area of ​​the front surface (4a) of the protective film (4) and the side of the substrate (W) which has the at least one recess (7); Applying pressure to the protective film (4) such that the protective film (4) enters the at least one recess (7) along at least part of a depth of the recess (7); Heating the protective film (4), wherein the pressure is applied to the protective film (4) during and / or after heating the protective film (4); and Processing one side (1) of the substrate (W) and / or the side (6) of the substrate (W) opposite one side (1).

Description

Technical field

[0001] The present invention relates to a method for processing a substrate, such as a wafer, for example a semiconductor wafer, which has at least one recess on one of its sides. Technical background

[0002] When processing a substrate, such as a semiconductor wafer, it is important to protect the substrate's sides from damage and contamination. This requirement is particularly critical if components, such as semiconductor devices, are located on one side of the substrate.

[0003] For example, in a semiconductor device manufacturing process, a wafer, which contains a component area with multiple components typically separated by several parting lines, serves as the substrate. This wafer is processed to divide the wafer into individual chips. This manufacturing process typically includes a grinding step to adjust the wafer thickness and a cutting step to cut the wafer along the parting lines to obtain the individual chips. The grinding step is performed from the back side of the wafer, which is opposite the front side where the component area is formed. Other processing steps, such as polishing and / or etching, can also be performed on the back side of the wafer. The wafer can be cut along the parting lines from either its front or back side.

[0004] Protection of one side of the substrate can be provided by attaching a protective film or cover.

[0005] In particular, to protect components formed on a wafer during processing of the wafer, for example from breakage, deformation and / or contamination by dirt particles, grinding water or cutting water, such a protective film or protective cover can be applied to the front of the wafer before processing.

[0006] Such protection of one side of the substrate is particularly important if there is a recess on the side, such as a groove, a slot, a cut, or the like. Firstly, such recesses are susceptible to contamination, for example, by dirt particles or water that can accumulate in them. Secondly, the presence of the recess can lead to an uneven distribution of pressure during processing, such as grinding, polishing, or cutting, thereby increasing the risk of mechanical damage to the substrate, such as substrate breakage.

[0007] Therefore, the use of a protective film or cover is of particular importance when working with substrates that have one or more cutouts on one side.

[0008] However, the side of the substrate to which the protective film or cover is applied can be damaged by the adhesive force of an adhesive layer formed on the protective film or cover, or contaminated by adhesive residue when the film or cover is removed from the substrate. In particular, such residue can remain in a recess formed on the substrate side. This is especially problematic if sensitive components, such as MEMS, are located on the side of the substrate to which the protective film or cover is applied. In this case, the component structure can be significantly compromised.

[0009] Consequently, there remains a need for a reliable and efficient method for processing a substrate with a recess on one of its sides, which makes it possible to minimize the risk of contamination and damage to the substrate.

[0010] EP 2 631 938 A1 discloses a film bonding method in which an adhesive film is applied to a surface of a wafer. JP 2004 - 217 757 A teaches a multilayer adhesive film. WO 2018 / 002 035 A2 discloses a method for processing a wafer with a first side having a component area and a second side opposite the first side having several protrusions. In this method, a protective film is applied to the second side of the wafer. Summary of the invention

[0011] Accordingly, an objective of the present invention is to provide a reliable and efficient method for processing a substrate with a recess on one of its sides, which makes it possible to minimize the risk of contamination and damage to the substrate. This objective is achieved by a substrate processing method with the technical features of claim 1. Preferred embodiments of the invention follow from the dependent claims.

[0012] The invention provides a method for processing a substrate. The substrate has one side, for example a front, and a side opposite that side, for example a back. The substrate has at least one recess on that side or on the side opposite that side. The method comprises providing a protective film or layer and applying the protective film or layer to the side of the substrate that has the at least one recess, such that at least a central region of a front surface of the protective film or layer is in direct contact with the side of the substrate that has the at least one recess, so that no adhesive is present between at least the central region of the front surface of the protective film and the side of the substrate that has the at least one recess.Furthermore, the method comprises applying pressure to the protective film or protective layer such that the protective film or protective layer enters the at least one recess along at least part of a depth of the recess, heating the protective film, wherein the pressure is applied to the protective film during and / or after heating the protective film, and processing one side of the substrate and / or the side of the substrate opposite that one side.

[0013] The protective film is applied to the side of the substrate that has the at least one recess, such that at least the central region of the front surface of the protective film or protective layer is in direct contact with the side of the substrate that has the at least one recess. Thus, no material, in particular no adhesive, is present between at least the central region of the front surface of the protective film and the side of the substrate that has the at least one recess.

[0014] Therefore, the risk of possible contamination or damage to the substrate, for example by the adhesive force of an adhesive layer or adhesive residues on the substrate, can be significantly reduced or even eliminated.

[0015] During and / or after the application of the protective film to the side of the substrate having the at least one recess, pressure is applied to the protective film so that it enters the recess along at least part of its depth. In this way, the protective film can be attached to the side of the substrate having the at least one recess. An adhesive force between the protective film and the substrate, which holds the protective film in position on the substrate, can be generated by applying pressure. Consequently, no additional adhesive material is required to attach the protective film to the side of the substrate having the at least one recess.

[0016] In particular, applying pressure to the protective film can create a form-fit connection, such as a positive-locking joint, and / or a material-locking connection, such as a material-locking joint, between the protective film and the substrate. The terms "material-locking joint" and "material-locking joint" define an attachment or connection between the protective film and the substrate based on atomic and / or molecular forces acting between these two components.

[0017] The term "material-bonded connection" refers to the presence of atomic and / or molecular forces that act in such a way as to attach or adhere the protective film to the substrate, and does not imply the presence of an additional adhesive between the protective film and the substrate. Rather, at least the central region of the front surface of the protective film is in direct contact with the side of the substrate that has the at least one recess, as explained above.

[0018] The substrate has at least one recess on one side or on the side opposite that side. The substrate may have multiple recesses on one side or on the side opposite that side. The at least one recess may, for example, be a groove, a slot, or a cut, such as a partial cut extending along part of the substrate's thickness. The at least one recess may extend inwards from a flat surface of the substrate, that is, in a direction from the surface towards the interior of the substrate.

[0019] The pressure is applied to the protective film in such a way that the protective film enters the recess along at least part of its depth. Consequently, the recess is reliably sealed and thus safely protected from contamination. Furthermore, at least part of the side walls of the recess is protected by the protective film.

[0020] The method according to the present invention thus enables reliable and efficient processing of a substrate with a recess on one of its sides, minimizing the risk of contamination and damage to the substrate.

[0021] The protective film can be applied to the side of the substrate that has the at least one recess in such a way that the front surface of the protective film is in direct contact with the side of the substrate that has the at least one recess in the entire area where the at least one recess is located. In this way, contamination of the recess, especially due to adhesive residue, can be reliably avoided.

[0022] The print can be applied to the protective film before processing one side of the substrate and / or the side of the substrate opposite that side.

[0023] The pressure can be applied to the protective film by a pressure application device, such as a roller, a roller assembly, a pressure plate, a stamp, a membrane or the like.

[0024] Applying pressure to the protective film can include or consist of applying a vacuum to the protective film during and / or after its application to the side of the substrate that has the at least one recess. A vacuum can be applied to the protective film in such a way that the protective film enters the at least one recess along at least a portion of its depth. This ensures with particular reliability that the protective film enters the at least one recess along at least a portion of its depth.

[0025] The pressure can be applied to the protective film in a vacuum chamber, as will be explained further below.

[0026] The protective film can be applied to and / or attached to the side of the substrate with the at least one recess in an atmosphere of reduced pressure, particularly under a vacuum. This ensures with particular reliability that the protective film enters the at least one recess along at least part of its depth and that no voids and / or air bubbles exist between the protective film and the substrate. Therefore, stress or strain on the substrate during processing of one side of the substrate and / or the side of the substrate opposite that side, for example due to the expansion of such air bubbles (e.g., during heating), is avoided.

[0027] For example, the step(s) of applying and / or attaching the protective film to the side of the substrate, which has at least one recess, can be carried out in a vacuum chamber.

[0028] In particular, the protective film can be applied to and / or attached to the side of the substrate that has the at least one recess using a vacuum laminator. In such a vacuum laminator, the substrate is positioned on a clamping table in a vacuum chamber in a state where the side of the substrate that does not have the at least one recess is in contact with an upper surface of the clamping table, and the side of the substrate that has the at least one recess faces upwards. The clamping table can, for example, be a heated clamping table.

[0029] The protective film, which is to be applied to the side of the substrate that has at least one recess, is held at its circumference by an annular frame and positioned above this substrate side in the vacuum chamber. An upper part of the vacuum chamber, located above the clamping table and the annular frame, is provided with an air inlet opening that is closed by an expandable rubber membrane.

[0030] After the substrate and protective film have been loaded into the vacuum chamber, the chamber is evacuated and air is supplied to the rubber membrane through the air inlet opening, causing the rubber membrane to expand into the evacuated chamber. This moves the rubber membrane downwards into the vacuum chamber, pressing the protective film against the side of the substrate that has the at least one recess, sealing the circumferential substrate section with the protective film, and pressing the film against the side of the substrate that has the at least one recess. Therefore, it can be reliably ensured that the protective film enters the at least one recess along at least a portion of its depth.

[0031] The protective film is heated, for example by heating the clamping table.

[0032] The vacuum in the vacuum chamber is then released, and the protective film is held in position on the side of the substrate with the at least one recess by the clamping force generated by the overpressure in the vacuum chamber and by a heating process. This heating process is described in more detail below.

[0033] Alternatively, the rubber membrane can be replaced by a soft stamp or roller, such as a heated soft stamp or a heated soft roller.

[0034] The substrate can be a wafer. Examples of suitable substrates include semiconductor wafers, glass wafers, sapphire wafers, ceramic wafers such as aluminum oxide (Al2O3) ceramic wafers, quartz wafers, zirconium oxide wafers, PZT (lead zirconate tanate) wafers, polycarbonate wafers, metal wafers (e.g., copper, iron, stainless steel, aluminum, or similar materials) or metallized material wafers, ferrite wafers, wafers made of optical crystal materials, wafers coated with or formed from a resin such as epoxy resin, or similar materials.

[0035] In particular, the substrate can be, for example, a Si wafer, a GaAs wafer, a GaN wafer, a GaP wafer, an InAs wafer, an InP wafer, a SiC wafer, a SiN wafer, an LT (lithium tantalate) wafer, an LN (lithium niobate) wafer or the like.

[0036] The substrate can consist of a single material or a combination of different materials, such as two or more of the materials mentioned above. For example, the substrate can be a silicon-glass composite substrate, such as a silicon-glass composite wafer, in which a silicon substrate element is bonded to a glass substrate element.

[0037] The substrate can be a semiconductor-sized wafer. Here, the term "semiconductor-sized wafer" refers to a wafer with the dimensions (standardized dimensions), in particular the diameter (standardized diameter), that is, the outer diameter, of a semiconductor wafer. The dimensions, especially the diameters, that is, the outer diameters, of semiconductor wafers are defined in the SEMI standards. For example, the semiconductor-sized wafer can be a silicon wafer. The dimensions of polished single-crystal silicon wafers are defined in the SEMI standards SEMI M1-1117 (Specification for Polished Single Crystal Silicon Wafers; pp. 1-68) and SEMI M76-0710 (Specification for Developmental 450 mm Diameter Polished Single Crystal Silicon Wafers; pp. 1-12). The semiconductor-sized wafer can be a 3-inch (76 mm), 4-inch (100 mm), 5-inch (125 mm), 6-inch (150 mm), 8-inch (200 mm), 12-inch (300 mm) or 18-inch (450 mm) wafer.

[0038] The substrate can have any type of shape. In a top view, the substrate can, for example, have a circular shape, an oval shape, an elliptical shape, or a polygonal shape, such as a rectangular shape or a square shape.

[0039] The protective film can have any shape. From a top view, the protective film can, for example, be circular, oval, elliptical, or polygonal, such as rectangular or square.

[0040] The protective film can essentially have the same shape as the substrate or the same shape as the substrate.

[0041] The protective film can have an outer diameter larger than the outer diameter of the substrate. This facilitates processing, handling, and / or transport of the substrate. In particular, an outer circumferential section of the protective film can be attached to an annular frame, as described below.

[0042] The protective film can have an outer diameter that is smaller than the outer diameter of the substrate.

[0043] The protective film can have an outer diameter that is essentially the same as the outer diameter of the substrate.

[0044] The substrate can have a component area with multiple components on one side. In particular, the substrate can be a wafer that has a component area with multiple components on one side.

[0045] The at least one recess can be located on one side of the substrate. The method according to the invention makes it possible to protect the components formed in the component area from damage and contamination in an efficient and reliable manner.

[0046] The substrate may also have a circumferential edge area on one side that does not contain any building elements and is formed around the building element area.

[0047] At least one dividing line can be formed on one side of the substrate. The at least one recess can extend along the at least one dividing line. Several dividing lines can be formed on one side of the substrate. Several recesses can be present on one side of the substrate. Each of the several recesses can extend along a corresponding one of the several dividing lines. The one or more dividing lines can separate components that can be formed on one side of the substrate. The method according to the invention makes it possible to protect the components, in particular the front and side surfaces of the components, from damage and contamination in an efficient and reliable manner.

[0048] The width of the at least one dividing line can be in the range of 30 µm to 200 µm, preferably 30 µm to 150 µm and more preferably 30 µm to 100 µm.

[0049] The method according to the invention comprises heating the protective film. In particular, the method can comprise heating the protective film and applying a vacuum to the protective film. In this case, the vacuum can be applied to the protective film during and / or before and / or after heating the protective film.

[0050] The process may further include allowing the protective film to cool down after the heating process. In particular, the protective film may be allowed to cool down to its initial temperature, that is, its temperature before the heating process. The protective film may be allowed to cool down, for example, to its initial temperature, before processing one side of the substrate, for example, the front of the substrate, and / or the side of the substrate opposite that side, for example, the back of the substrate.

[0051] An adhesive force between the protective film and the substrate can be generated by the heating process. The adhesion of the protective film to the substrate can be achieved during the heating process itself and / or in a subsequent cooling process.

[0052] The protective film can be softened by the heating process. Upon cooling, for example to its initial temperature, the protective film can harden again, for example in such a way that a form fit and / or a material bond with the substrate is created.

[0053] By softening the protective film through a heating process, it can be ensured particularly reliably that the protective film enters at least one recess along at least part of the depth of the recess.

[0054] The protective film can be heat-resistant up to a temperature of 180 °C or more, preferably up to a temperature of 220 °C or more, more preferably up to a temperature of 250 °C or more and even more preferably up to a temperature of 300 °C or more.

[0055] The protective film 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. It is particularly preferred that the protective film be heated to a temperature of approximately 80 °C.

[0056] The protective film can be heated for a period of time ranging from 30 seconds to 10 minutes, preferably 1 minute to 8 minutes, more preferably 1 minute to 6 minutes, even more preferably 1 minute to 4 minutes and even more preferably 1 minute to 3 minutes during and / or after the application of the protective film to the side of the substrate which has the at least one recess.

[0057] The protective film can be heated directly and / or indirectly.

[0058] 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 punch, or the like, or a heat dissipation device. The protective film and the substrate can be arranged in a receptacle or chamber, such as a vacuum chamber, and an internal volume of the receptacle or chamber can be heated so that the protective film is heated. The receptacle or chamber can be equipped with a heat dissipation device.

[0059] The protective film can be heated indirectly, for example by heating the substrate before, during, and / or after applying the protective film to the side of the substrate that has at least one cutout. For example, the substrate can be heated by placing it on a support or carrier, such as a clamping table, and then heating the support or carrier.

[0060] For example, the support or substrate, such as a clamping 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 substrate can be heated to a temperature of approximately 80 °C.

[0061] These approaches can also be combined, for example by using a heat application device, such as a heated roller or the like, or a heat radiation device to directly heat the protective film, and also by indirectly heating the protective film through the substrate.

[0062] It is preferred that the protective film be pliable, elastic, flexible, stretchable, soft, and / or compressible. The protective film can be pliable, elastic, flexible, stretchable, soft, and / or compressible at room temperature, for example, in the temperature range of 18 to 23 °C, and / or when it is in its heated state. It is particularly preferred that the protective film be pliable, elastic, flexible, stretchable, soft, and / or compressible at room temperature, and that the pliability, elasticity, flexibility, stretchability, softness, and / or compressibility of the protective film is further increased when it is in its heated state.

[0063] In this way, it can be ensured particularly reliably that the protective film enters at least one recess along at least part of the depth of the recess.

[0064] Preferably, the protective film hardens or stiffens at least to a certain extent upon cooling, so that it becomes stiffer and / or more robust in the cooled state. In this way, particularly reliable protection of the substrate can be ensured during subsequent processing of the substrate, such as grinding and / or cutting.

[0065] The print is applied to the protective film during and / or after heating.

[0066] A combined heat and pressure application device, such as a heated roller, a heated printing plate, or a heated stamp, is particularly advantageous. In this case, pressure can be applied to the protective film while the protective film is simultaneously heated.

[0067] The print can be applied to the protective film in such a way that the protective film has at least one recess to a depth of 3 to 500 µm, preferably 5 to 300 µm, in particular 5 to 50 µm.

[0068] The minimum of one recess can have a depth, i.e., an extent along the thickness direction of the substrate, in the range of 5 to 1500 µm, or in the range of 50 to 1000 µm, or in the range of 100 to 800 µm. The minimum of one recess can have a depth in the range of 2% to 90%, or in the range of 5% to 70%, or in the range of 8% to 50%, or in the range of 10% to 40%, or in the range of 12% to 30% of the substrate thickness.

[0069] The print can be applied to the protective film such that the protective film penetrates the depth of the at least one recess to a depth of 2% to 100%, preferably 5% to 90%, more preferably 10% to 80%, even more preferably 15% to 70%, and even more preferably 20% to 60%. The method according to the invention can further comprise removing substrate material from one side of the substrate or from the side of the substrate opposite that side in order to form the at least one recess.

[0070] For example, substrate material can be removed by mechanical cutting, such as blade cutting or sawing, and / or by laser cutting and / or plasma cutting and / or by etching, such as wet or dry etching, and / or lithography, such as optical lithography or electron beam lithography. The substrate material can be removed in a single mechanical cutting step, a single laser cutting step, a single plasma cutting step, a single etching step, or a single lithographic step. Alternatively, the substrate material can be removed by a sequence of two or more of the above steps.

[0071] Laser cutting can be performed, for example, by ablation laser cutting and / or stealth laser cutting, that is, by creating modified areas within the substrate by applying a laser beam, and / or by creating multiple opening areas in the substrate by applying a laser beam. Each of these opening areas can consist of a modified area and a space within the modified area that is open to a surface of the substrate.

[0072] At least one recess can be formed by removing substrate material along at least one separation line, if at least one such separation line exists. If multiple separation lines exist, multiple recesses can be formed by removing substrate material along each of the separation lines.

[0073] The substrate material can be removed along a portion of the substrate thickness, for example, along 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the substrate thickness. The substrate material can also be removed along 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the substrate thickness.

[0074] The method according to the invention can include machining the side of the substrate opposite one side. Machining the side of the substrate opposite one side can include grinding the side of the substrate opposite one side to adjust the substrate thickness.

[0075] The process may further include polishing, such as dry polishing or chemical-mechanical polishing (CMP), and / or etching, such as wet etching or dry etching, such as plasma etching, of the side of the substrate opposite one side. If the side of the substrate opposite one side is subjected to a grinding step, the polishing and / or etching steps may be performed after the grinding.

[0076] The process can further involve dividing the substrate into several separate elements. For example, the substrate can be a wafer that has a component area with multiple components on one side. The process can involve dividing the wafer into several individual components or chips. For example, the substrate can be divided into several separate elements, such as individual components or chips, in the following ways.

[0077] Substrate material can be removed, for example along at least one dividing line, if present, to form the at least one recess. The substrate material removal step can be carried out, for example, in the manner described above. The substrate material removal process can be performed from one side of the substrate. The protective film can be applied to the side of the substrate that has the at least one recess formed therein. Subsequently, the side of the substrate opposite the side with the at least one recess can be sanded to adjust the substrate thickness. The substrate material can be removed along only a portion of the substrate's thickness.Grinding of the side of the substrate opposite the side with the at least one recess can be carried out along a remaining portion of the substrate thickness in which no wafer material has been removed, so that the substrate is divided, for example along the at least one dividing line.

[0078] Alternatively, the substrate can be completely divided into several separate elements, such as individual building blocks or chips, by cutting it, for example along at least one dividing line, if one exists. The substrate can be cut from the side opposite the side with the at least one recess. The cutting operation can be carried out before or after grinding the side of the substrate opposite the side with the at least one recess.

[0079] The cutting step can be carried out, for example, in the manner described above, such as by mechanical cutting, like blade cutting or sawing, and / or by laser cutting and / or by plasma cutting and / or by etching, for example wet etching or dry etching.

[0080] Laser cutting can be performed, for example, by ablation laser cutting and / or stealth laser cutting, that is, by creating modified areas within the substrate by applying a laser beam, and / or by creating multiple openings in the substrate by applying a laser beam. Each of these openings can consist of a modified area and a space within the modified area that is open to a surface of the substrate. After creating the modified areas or the openings in the substrate, the substrate can be completely separated by applying an external force in the radial directions of the substrate, for example, by radially expanding a spreading strip. For example, the protective film can be used as such a spreading strip.

[0081] Furthermore, the substrate can be divided into separate elements by scoring the substrate, for example by using a diamond scoring device, a laser scoring device or the like, and subsequently breaking the substrate by applying an external force to it.

[0082] The substrate can be divided into separate elements by a combination of the processes described above. For example, the side of the substrate opposite the side with the at least one recess can be partially cut mechanically with a first cutting width, and a remaining portion of the substrate in its thickness direction, in the area(s) where the partial cut(s) was / were made, can be mechanically cut and / or laser-cut and / or plasma-cut from the side of the substrate opposite the side with the at least one recess with a second cutting width. The second cutting width can be smaller than or equal to the first cutting width.Subsequently, the side of the substrate opposite the side with at least one recess can be ground, for example to remove any damage caused by the partial mechanical cutting step.

[0083] The process can further include picking up the separated elements, such as individual building blocks or chips, from the protective film. This picking step can be carried out using a picking device.

[0084] In the method according to the present invention, the protective film is applied to the side of the substrate having the at least one recess such that at least the central area of ​​the front surface of the protective film is in direct contact with the side of the substrate having the at least one recess. Consequently, the step of picking up the separated elements is greatly facilitated due to the absence of an adhesive layer, at least in this central area. In particular, the risk of damage to the separated elements during the picking step can be significantly reduced or even eliminated. Furthermore, the force required to pick up the separated elements from the protective film is considerably reduced.

[0085] Furthermore, in the present method, pressure is applied to the protective film such that the protective film enters the at least one recess along at least part of its depth. In this way, the protective film can securely hold the substrate in its position before it is cut and, after the substrate is cut, securely hold the separated elements, such as individual building blocks or chips, in their positions. Consequently, movement or displacement of the substrate or these separated elements during process steps, such as grinding or picking up the elements, can be reliably prevented. In particular, since no such movement or displacement occurs during grinding, a particularly precise and simple alignment can be achieved in any subsequent cutting, severing, or picking steps.For example, due to this high degree of alignment accuracy, the substrate can be reliably cut from one side or the side opposite that side by using a thin mechanical cutting tool, such as a thin blade or a thin saw.

[0086] The protective film can be applied to the side of the substrate having the at least one recess in such a way that, throughout the entire area where the front surface of the protective film is in contact with the side of the substrate having the at least one recess, the front surface of the protective film is in direct contact with the side of the substrate having the at least one recess. Thus, no material, in particular no adhesive, is present between the front surface of the protective film and the side of the substrate having the at least one recess.

[0087] In this way, the risk of possible contamination or damage to the substrate, for example due to the adhesive force of an adhesive layer or adhesive residues on the substrate, can be reliably eliminated.

[0088] Alternatively, the protective film can be provided with an adhesive layer. In this case, the adhesive layer is applied only to a circumferential region of the front surface of the protective film, with the circumferential region surrounding the central region of the front surface of the protective film. The protective film is applied to the side of the substrate that has the at least one recess in such a way that the adhesive layer comes into contact only with a circumferential section of the side of the substrate that has the at least one recess. The circumferential section of the side of the substrate that has the at least one recess can be or correspond to a circumferential edge region formed on one side of the substrate, for example, if the substrate is a wafer that has a component area with multiple components on one side.

[0089] This method further improves the adhesion of the protective film to the substrate. Since the adhesive layer is only applied to the perimeter of the protective film's front surface, the area where the film and substrate adhere to each other is significantly reduced compared to a case where the adhesive layer covers the entire front surface. Therefore, the protective film can be removed more easily from the substrate, and the risk of damaging the substrate is considerably reduced.

[0090] The adhesive layer can be cured by an external stimulus, such as heat, UV radiation, an electric field, and / or a chemical substance. This allows the protective film to be removed from the substrate particularly easily after processing. The external stimulus can be applied to the adhesive, reducing its adhesive strength and thus facilitating easy removal of the protective film. Furthermore, separate elements, such as individual components or chips, can be easily picked up from the protective film.

[0091] For example, the adhesive layer can have an essentially ring-shaped form, an open rectangular form, or an open square form, that is, a rectangular or square form with an opening in the middle of the adhesive layer.

[0092] A damping layer can be applied to a rear surface of the protective film that faces its front surface.

[0093] This approach is particularly advantageous, for example, if protrusions or elevations, such as bumps, optical elements (e.g., optical lenses), other structures, or the like, protrude from, extend from, or project from the side of the substrate which has at least one recess, along the thickness direction of the substrate.

[0094] If the damping layer is applied to the rear surface of the protective film, such protrusions can be embedded within the damping layer. Therefore, any negative impact of the protrusions on subsequent substrate processing steps, such as cutting, polishing, or grinding, can be eliminated. In particular, the damping layer can significantly contribute to achieving a particularly even and uniform pressure distribution during such processes.

[0095] By embedding the protrusions in the damping layer, the protrusions, such as optical elements or other structures, are reliably protected from damage during substrate processing, for example in a subsequent cutting or grinding step.

[0096] The material of the damping layer is not particularly restricted. In particular, the damping layer can be made of any type of material that allows for the embedding of protrusions along the thickness direction of the substrate. For example, the damping layer can be made of a resin, an adhesive, a gel, or the like.

[0097] The damping layer can be cured by an external stimulus, such as UV radiation, heat, an electric field, and / or a chemical substance. In this case, the damping layer cures, at least to a certain degree, when the external stimulus is applied. For example, the damping layer can be made of a curable resin, a curable adhesive, a curable gel, or the like.

[0098] The damping layer can be designed to exhibit a certain degree of compressibility, elasticity, and / or flexibility after curing. For example, the damping layer can be designed to cure into a rubber-like state. Alternatively, the damping layer can be designed to achieve a stiff, hard state after curing.

[0099] Preferred examples of UV-curing resins for use as a damping layer in the method according to the invention are ResiFlat ® from DISCO Corporation and TEMPLOC ® by DENKA.

[0100] The process can further include applying an external impulse to the damping layer to harden it, for example, before processing the substrate, such as cutting or grinding. This can further improve substrate protection during cutting and / or grinding, as well as cutting and / or grinding accuracy.

[0101] The damping layer can be heat-resistant up to a temperature of 180 °C or more, preferably up to a temperature of 220 °C or more, more preferably up to a temperature of 250 °C or more and even more preferably up to a temperature of 300 °C or more.

[0102] The damping layer can have a thickness in the range of 10 to 300 µm, preferably 20 to 250 µm and more preferably 50 to 200 µm.

[0103] The damping layer can be applied to the rear surface of the protective film before the protective film is applied to the side of the substrate which has at least one recess.

[0104] In this case, the protective film and the damping layer can first be layered, forming a protective cover that encompasses the damping layer and the protective film attached to the damping layer. The protective cover formed in this way can then be applied to the side of the substrate that has the at least one recess, for example, such that protrusions or bumps that extend from the flat surface of the wafer are covered by the protective film and embedded within the protective film and the damping layer.

[0105] The protective cover can be applied such that the rear surface of the damping layer is substantially parallel to the side of the substrate opposite the side with the at least one recess. The front surface of the protective film is applied to the side of the substrate having the at least one recess when the protective cover is applied to that side.

[0106] In this way, the substrate processing procedure can be carried out in a particularly simple and efficient manner. For example, the protective cover can be prepared in advance, stored for later use, and used for substrate processing when required. The protective cover can therefore be manufactured in large quantities, making its production particularly efficient in terms of both time and cost.

[0107] The damping layer can be applied to the rear surface of the protective film after the protective film has been applied to the side of the substrate which has at least one recess.

[0108] In this case, the protective film is first applied to the side of the substrate having the at least one recess, and subsequently, the side of the substrate with the at least one recess, bearing the protective film applied thereto, is attached to the front surface of the damping layer, for example, such that protrusions or ridges projecting from the flat surface of the substrate are embedded in the protective film and the damping layer, and the rear surface of the damping layer is substantially parallel to the side of the substrate opposite the side with the at least one recess. This approach makes it possible to apply the protective film with a particularly high degree of accuracy to the side of the substrate having the at least one recess, especially with regard to protrusions or ridges projecting from the flat surface of the wafer.

[0109] The damping layer can be applied to the rear surface of the protective film before and / or during and / or after the protective film is applied to the side of the substrate which has at least one recess.

[0110] Pressure can be applied to the damping layer so that the damping layer enters the at least one recess along at least part of the depth of the recess.

[0111] A base layer can be applied to the rear surface of the damping layer, which is opposite its front surface that is attached to the protective film.

[0112] The material of the base layer is not particularly restricted. The base layer can consist of a soft or flexible material, such as a polymer material, for example polyvinyl chloride (PVC), ethylene vinyl acetate (EVA), or a polyolefin.

[0113] Alternatively, the base layer can consist of a rigid or hard material, such as polyethylene terephthalate (PET) and / or silicon and / or glass and / or stainless steel (SUS).

[0114] For example, if the base layer is made of polyethylene terephthalate (PET) or glass and the damper layer is curable by an external impulse, the damper layer can be cured with radiation that can be transmitted through polyethylene terephthalate (PET) or glass, such as UV radiation. If the base layer is made of silicon or stainless steel (SUS), a cost-effective base layer is provided.

[0115] The base layer can also be made from a combination of the materials listed above.

[0116] The base layer can be heat-resistant up to a temperature of 180 °C or more, preferably up to a temperature of 220 °C or more, more preferably up to a temperature of 250 °C or more and even more preferably up to a temperature of 300 °C or more.

[0117] The base layer can have a thickness in the range of 30 to 1500 µm, preferably 40 to 1200 µm and more preferably 50 to 1000 µm.

[0118] The damping layer and the base layer can be applied to the rear surface of the protective film either before or after the protective film is applied to the side of the substrate that has at least one recess. In particular, the protective film, the damping layer, and the base layer can first be layered, forming a protective cover that includes the base layer, the damping layer, and the protective film attached to the damping layer. This protective cover can then be applied to the side of the substrate that has at least one recess.

[0119] The front surface of the base layer can be in contact with the rear surface of the damping layer, and a rear surface of the base layer opposite its front surface can be substantially parallel to the side of the substrate opposite the side with the at least one recess. Therefore, when the substrate is machined, such as by cutting or grinding, suitable counter-pressure can be applied to the rear surface of the base layer, for example by placing this rear surface on a clamping table.

[0120] In this case, since the flat rear surface of the base layer is essentially parallel to the side of the substrate opposite the side with the at least one recess, the pressure exerted on the substrate during machining, such as a cutting operation (e.g., by a cutting or dividing blade of a cutting device) or a grinding operation, is distributed more evenly and uniformly across the substrate, thus minimizing the risk of substrate breakage. Furthermore, the essentially parallel alignment of the flat, uniform rear surface of the base layer and the side of the substrate opposite the side with the at least one recess allows cutting and grinding operations to be carried out with a high degree of accuracy.

[0121] The protective film can consist of a single material, in particular a single homogeneous material.

[0122] The protective film can be made of a plastic material, such as a polymer. Preferably, the protective film is made of a polyolefin. For example, the protective film can be made of polyethylene (PE), polypropylene (PP), or polybutylene (PB).

[0123] Polyolefin films possess material properties that are particularly advantageous for use in the substrate processing method according to the present invention, especially since the method includes heating the protective film. Polyolefin films are flexible, stretchable, and soft, particularly when heated, for example, to a temperature in the range of 60 °C to 150 °C. Therefore, it can be ensured with particular reliability that the protective film enters the at least one recess along at least a portion of its depth.

[0124] Furthermore, polyolefin films harden and stiffen upon cooling, becoming stiffer and more robust in their cooled state. This ensures particularly reliable protection of the substrate during subsequent wafer processing.

[0125] The protective film can have a thickness in the range of 5 to 200 µm, preferably 8 to 100 µm, more preferably 10 to 80 µm, and even more preferably 12 to 50 µm. Particularly preferably, the protective film has a thickness in the range of 80 to 150 µm.

[0126] In this way, it can be ensured particularly reliably that the protective film is flexible and pliable enough to enter at least one recess along at least part of the depth of the recess, and at the same time has sufficient thickness to reliably and efficiently protect the substrate during processing.

[0127] The method can further include attaching a circumferential section of the protective film to an annular frame. In particular, the circumferential section of the protective film can be attached to the annular frame such that the protective film closes a central opening of the annular frame, that is, the area within the inner diameter of the annular frame. In this way, the substrate, which is attached to the protective film, especially to a central section thereof, is held by the protective film within the annular frame. Therefore, a substrate unit is formed comprising the substrate, the protective film, and the annular frame, thereby facilitating the processing, handling, and / or transport of the substrate.

[0128] The step of attaching the circumferential section of the protective film to the ring-shaped frame can be carried out before or after applying the protective film to the substrate.

[0129] The step of attaching the circumferential section of the protective film to the ring-shaped frame can be carried out before or after attaching the protective film to the substrate.

[0130] The step of attaching the circumferential section of the protective film to the ring-shaped frame can be carried out before or after processing one side of the substrate and / or the side of the substrate opposite that side.

[0131] The ring-shaped frame can be a semiconductor-sized ring-shaped frame. Here, the term "semiconductor-sized ring-shaped frame" refers to a ring-shaped frame with the dimensions (standardized dimensions), in particular the inner diameter (standardized inner diameter), of a ring-shaped frame for holding a semiconductor wafer.

[0132] The dimensions, particularly the inner diameters, of annular frames for holding semiconductor wafers are defined in the SEMI standards. For example, the dimensions of tape frames for 300 mm wafers are defined in the SEMI standard SEMI G74-0699 (Reapproved 0215; Specification for Tape Frame for 300 mm Wafers; pp. 1-5), and the dimensions of plastic tape frames for 300 mm wafers are defined in the SEMI standard SEMI G87-1108 (Reapproved 0215; Specification for Plastic Tape Frame for 300 mm Wafer; pp. 1-4). The ring-shaped frames can have frame sizes for holding semiconductor-sized wafers, for example, 3 inches (76 mm), 4 inches (100 mm), 5 inches (125 mm), 6 inches (150 mm), 8 inches (200 mm), 12 inches (300 mm), or 18 inches (450 mm).

[0133] Attaching the circumferential section of the protective film to a ring-shaped frame the size of a semiconductor offers the advantage that conventional semiconductor wafer handling and processing equipment, such as a conventional pick-up device, can be used to handle and process the substrate and the separated elements, such as individual components or chips.

[0134] In the method according to the present invention, the protective film can remain attached to the substrate throughout the entire processing process. Therefore, the same protective film can be used continuously throughout the entire process, for example, until the separated elements, such as individual building blocks or chips obtained by dividing the substrate, are picked up by the protective film. In this case, no steps of removing the protective film from the substrate and reattaching the substrate to a different film or tape are required. Therefore, the processing method can be greatly simplified. Furthermore, due to the reduced number of substrate handling and processing steps required, the risk of substrate damage can be further reduced. Moreover, this approach is particularly efficient, for example, with regard to processing time and costs.

[0135] The protective film can be expandable. The protective film can be expanded when it is applied to the side of the substrate that has the at least one recess. In this way, it can be ensured with particular reliability that the protective film enters the at least one recess along at least a portion of its depth. In particular, the protective film can be expandable to twice its original size or more, preferably to three times its original size or more, and more preferably to four times its original size or more.

[0136] If the protective film is expandable, it can be used to separate the elements obtained by dividing the substrate, such as building blocks or chips. In particular, the method can further include radially expanding the protective film after processing one side of the substrate and / or the side of the substrate opposite that side, in order to separate the elements from one another.

[0137] For example, the substrate can be completely divided, for instance by a mechanical cutting process, a laser cutting process, a plasma cutting process, or by a pre-grinding process. Subsequently, the completely divided elements, such as building blocks or chips, can be moved away from each other by radially expanding the protective film, thereby increasing the distances between adjacent elements.

[0138] Alternatively, the substrate can be subjected to a stealth sectioning process, that is, a process in which modified areas are formed within the wafer by applying a laser beam, as described above. Subsequently, the substrate can be divided, for example, by radially expanding the protective film, along at least one dividing line where the modified areas are formed, thus yielding the separated elements.

[0139] As an alternative to radially expanding the protective film, a separate expanding tape can be used. Brief description of the drawings

[0140] Non-limiting examples of the invention are discussed below with reference to the drawings, wherein: Fig. 1 is a cross-sectional representation illustrating a step of applying a protective film to a substrate in a method for processing the substrate according to an embodiment of the present invention; Fig. 2 is a cross-sectional representation that shows the result of the in Fig. The first illustrated step shows; Fig. 3 an enlarged cross-sectional view of the circled area in Fig. 2 in the method for processing the substrate according to the embodiment of the present invention; Fig. 4 an enlarged cross-sectional view of the circled area in Fig. 2 in a modification of the method for processing the substrate according to the embodiment of the present invention; Fig. 5 is a cross-sectional representation illustrating a step of the grinding of the substrate in the method for processing the substrate according to the embodiment of the present invention; Fig. 6 is a cross-sectional representation illustrating one step of dividing the substrate into several separate elements in the method for processing the substrate according to the embodiment of the present invention; Fig. 7 is a cross-sectional representation that shows the result of the in Fig. The 6 illustrated steps show; and Fig. Figure 8 is a cross-sectional representation illustrating one step of picking up the separated elements from the protective film in the method for processing the substrate according to the embodiment of the present invention. Detailed description of a preferred embodiment

[0141] A preferred embodiment of the present invention is described below with reference to the accompanying drawings. The preferred embodiment relates to a method for processing a wafer W as an exemplary embodiment of a substrate. The method according to the preferred embodiment can also be applied to substrates other than wafers. The substrate to be processed by this method is not limited to wafers.

[0142] The wafer W can, for example, be a MEMS wafer that has MEMS devices formed on the surface of a front face 1 of the same (see Fig. 1) However, the wafer W is not limited to a MEMS wafer, but can also be a CMOS wafer having CMOS components, preferably as solid-state imaging devices, formed on its front face 1, or a wafer with other types of components on its front face 1. The method according to the preferred embodiment can also be applied to substrates that do not have any components formed on them.

[0143] The wafer W can consist of a semiconductor, such as silicon (Si). Such a silicon wafer W can contain devices, such as ICs (integrated circuits) and LSIs (low-level integrated circuits), on a silicon substrate. Alternatively, the wafer W can be an optical device wafer, which is built up by forming optical devices, such as LEDs (light-emitting diodes), on a substrate of inorganic material, such as ceramic, glass, or sapphire. The wafer W is not limited to these options and can be configured in any other way. Furthermore, a combination of the above-described exemplary wafer configurations is also possible.

[0144] The wafer W can have a thickness in the µm range, preferably in the range of 625 to 925 µm, before grinding.

[0145] The wafer W preferably has a circular shape. However, the shape of the wafer W is not particularly restricted. In other embodiments, the wafer W can, for example, have an oval shape, an elliptical shape, or a polygonal shape, such as a rectangular or square shape.

[0146] The wafer W is provided with several intersecting dividing lines 11, also referred to as roads (see Fig. 1) which are formed on its front face 1, thereby dividing the wafer W into several rectangular areas, each containing components 27, such as those described above. These components 27 are formed in a component area 2 of the wafer W. In the case of a circular wafer W, this component area 2 is preferably arranged circularly and concentrically to the outer circumference of the wafer W. The method according to the preferred embodiment can also be applied to substrates that do not have any components formed on them. For example, instead of the components 27, a sensitive surface layer requiring protection can be present on the front face 1 of the substrate between the dividing lines 11.

[0147] The component area 2 is surrounded by an annular circumferential edge area 3, as shown in Fig. Figure 1 shows a schematic representation. No components are formed in this circumferential edge region 3. The circumferential edge region 3 is preferably arranged concentrically to the component region 2 and / or the outer circumference of the wafer W. The radial extent of the circumferential edge region 3 can be in the millimeter range and preferably ranges from 1 to 3 mm.

[0148] The wafer W also has a back side 6, which is opposite the front side 1 (see Fig. 1).

[0149] Several recesses 7 are formed on the front face 1 of the wafer W. Each of the recesses 7 extends along a corresponding parting line 11. The recesses 7 can be grooves, slots, or cuts, that is, partial cuts extending along a portion of the wafer W's thickness. For example, the recesses 7 can be formed by removing wafer material along the parting lines 11, such as by mechanical cutting, like blade cutting or sawing, and / or by laser cutting and / or plasma cutting and / or by etching, for example, wet etching or dry etching, and / or by lithography, such as optical lithography or electron beam lithography. The recesses 7 extend inwards from a flat surface of the wafer W.

[0150] The following describes the method for processing the wafer W according to the embodiment of the present invention with reference to Fig. 1 to 8 described.

[0151] A protective film 4 is provided, as shown in Fig. Figure 1 shows the following. For example, the protective film 4 can have a thickness in the range of 5 to 200 µm. The protective film 4 is made of a polyolefin. For example, the protective film 4 can be made of polyethylene (PE) or polypropylene (PP). The protective film 4 has a front surface 4a and a rear surface 4b facing it (see Figure 1). Fig. 1).

[0152] An adhesive layer 9 is applied to a portion of the front surface 4a of the protective film 4. Specifically, the adhesive layer 9 is circular in shape and is only present in a peripheral or circumferential region of the front surface 4a of the protective film 4. This peripheral or circumferential region surrounds a central area of ​​the front surface 4a of the protective film 4. In other embodiments, the adhesive layer 9 can be omitted. In this case, the front surface 4a of the protective film 4 can be in direct contact with the front surface 1 of the wafer W in the entire area where the front surface 4a of the protective film 4 is in contact with the front surface 1.

[0153] Fig. Figure 1 illustrates one step of applying the protective film 4 to the front side 1 of the wafer W.

[0154] As in Fig. As shown in Figure 1, the annular adhesive layer 9 has an outer diameter that is larger than the inner diameter of an annular frame 25. Furthermore, the annular adhesive layer 9 has an inner diameter that is smaller than the outer diameter of the wafer W but larger than the outer diameter of the component area 2. Therefore, it can be reliably ensured that the adhesive of the adhesive layer 9 only comes into contact with the circumferential edge region 3 on the front face 1 of the wafer W, in which no components are formed.

[0155] Before the protective film 4 is applied to the wafer W, a circumferential section of the protective film 4 is attached to the annular frame 25 by the adhesive layer 9. The annular frame 25 can be a semiconductor-sized ring frame. The following is described as in Fig. 1 is indicated by an arrow, the protective film 4 is applied to the front side 1 of the wafer W and the protective film 4 is adhered to the circumferential section of the front side 1 by the adhesive layer 9.

[0156] The adhesive forming the adhesive layer 9 can be cured by an external stimulus, such as heat, UV radiation, an electric field, and / or a chemical substance. This allows the protective film 4 to be removed from the wafer W particularly easily after processing.

[0157] In particular, the adhesive can be an acrylic resin or an epoxy resin. A preferred example of a UV-curing resin for the adhesive is urethane acrylate oligomer.

[0158] Furthermore, the adhesive can be, for example, a water-soluble resin.

[0159] The protective film 4 is applied to the front surface 1 of the wafer W in such a way that the central area of ​​the front surface 4a of the protective film 4, i.e. the area of ​​the front surface 4a within the annular adhesive layer 9, is in direct contact with the front surface 1 of the wafer W (see Fig. 2) Thus, there is no material, in particular no adhesive, between the middle area of ​​the front surface 4a of the protective film 4 and the front side 1 of the wafer W.

[0160] Subsequently, pressure is applied to the protective film 4 so that the protective film 4 enters the recesses 7 along at least part of a depth of the recesses 7, as described below with reference to Fig. 3 and Fig. 4 is explained in more detail. By applying pressure, the protective film 4 is also attached to the front surface 1 of the wafer W in the central area of ​​the front surface 4a. An adhesion force between the protective film 4 and the wafer W is generated by the application of pressure.

[0161] In the present embodiment, applying pressure to the protective film 4 consists of applying a vacuum to the protective film 4 during and / or after its application to the front surface 1 of the substrate. The vacuum is applied to the protective film 4 such that the protective film 4 enters the recesses 7 along at least a portion of their depth. This ensures with particular reliability that the protective film 4 enters the recesses 7 along at least a portion of their depth. The vacuum can be applied to the protective film 4 in a vacuum application device, such as a vacuum chamber (not shown).

[0162] The protective film 4 is heated. The vacuum is applied to the protective film 4 during and / or after heating.

[0163] An adhesive force between the protective film 4 and the wafer W can be generated by the heating process. The adhesion of the protective film 4 to the wafer W can be achieved during the heating process itself and / or in a subsequent cooling process of the protective film 4.

[0164] The protective film 4 can be softened by the heating process. Upon cooling, for example to its initial temperature, the protective film 4 can harden again, for example in such a way that a form fit and / or a material bond with the wafer W is created. By softening the protective film 4 through the heating process, it can be ensured particularly reliably that the protective film 4 enters the recesses 7 along at least part of their depth.

[0165] The result of the process of applying the protective film 4 to the front 1 of the wafer W is in Fig. 2 shown. Fig. 3 and Fig. Figure 4 shows enlarged cross-sectional views of the circled area in Fig. 2 in the method for processing the wafer W according to the embodiment of the present invention or in a modification thereof.

[0166] In the method according to the present embodiment, the recesses 7 have a depth, i.e., an extent along the thickness direction of the wafer W, of approximately 50% of the wafer thickness. The protective film 4 penetrates the recesses 7 to a depth of approximately 50% of the depth of the recesses 7, as shown in Fig. Figure 3 illustrates this.

[0167] In the modified method according to the present embodiment, no components are present on the front face 1 of the wafer W. Instead, a continuous, sensitive surface layer 29 is formed on the front face 1 (see Fig. 4) Furthermore, the depth of the recesses 7 is considerably smaller than that of the ones in Fig. 3 shown embodiment, namely approximately 10% of the wafer thickness. The protective film 4 enters the recesses 7 along the entire depth of the recesses 7, as shown in Fig. 4 is shown.

[0168] After applying the protective film 4 to the front 1 of the wafer W, the back 6 of the wafer W is ground to adjust the wafer thickness, as shown in Fig. 5 is indicated by an arrow. During the grinding process, the front side 1 is reliably protected from damage and contamination by the protective film 4. In particular, because the protective film 4 extends into the recesses 7 along part of their depth, it can hold the wafer W particularly securely in position, preventing any movement or displacement, such as chip shifting. Therefore, the accuracy of subsequent processing and handling steps, such as cutting, slicing, or picking, can be significantly increased.

[0169] Optionally, the method according to the present embodiment can further include polishing, for example dry polishing or chemical-mechanical polishing (CMP), and / or etching, for example wet etching or dry etching, such as plasma etching, of the back side 6 of the wafer W. The polishing and / or etching steps can be performed after grinding. The polishing and / or etching steps can be performed before dividing the wafer W.

[0170] The in Fig. The illustrated grinding step 5 is followed by a step of dividing the wafer W into separate individual chips 30 (see Fig. 7) Specifically, as in Fig. 6, indicated by an arrow, the wafer W is cut from its back side 6 using a cutting blade 32 along the dividing lines 11 in order to completely divide the wafer W. The result of this division step is shown in Fig. Figure 7 shows. Alternatively, the wafer can be cut, for example, by a laser cutting process, a plasma cutting process, or by a splitting process prior to grinding, as explained above.

[0171] During the wafer W splitting process, the partial extension of the protective film 4 into the recesses 7 also provides reliable protection for the side walls of the resulting chips 30. Furthermore, after the wafer W has been split, the protective film 4 securely holds the chips 30 in their positions, thus greatly facilitating the subsequent step of picking up the chips 30. In particular, this picking step can be carried out easily and with a very high degree of accuracy.

[0172] In other embodiments, the wafer W or another type of substrate can be divided in various ways, as described above. For example, a cutting step of the wafer W or other type of substrate can be performed before grinding the wafer W or the substrate. Furthermore, in some embodiments, no grinding of the wafer W or other type of substrate is performed.

[0173] After the wafer W is divided into the separate chips 30, the chips 30 are picked up individually using a pickup device 40, as shown in Fig. Figure 8 shows the pickup device 40 comprising a pickup head 42 and a lift-up pin 44. During the pickup process, the chip 30 to be picked up is first pushed upwards from the side of the rear surface 4b of the protective film 4 by the lift-up pin, as shown in Figure 8. Fig. 8 is indicated by an arrow. In this way, the chip 30 is lifted and can therefore be easily accessed by the pick-up head 42. Subsequently, the pick-up head 42 picks up the chip 30, for example by vacuum suction, and removes it from the remaining part of the split wafer W, as indicated by another arrow in Fig. 8 is displayed.

[0174] As explained above, the protective film 4 is attached to the wafer W in such a way that the adhesive of the adhesive layer 9 only comes into contact with the peripheral edge region 3 on the front face 1 of the wafer W, where no components are formed. No adhesive is present in the component area 2. This greatly simplifies the chip pick-up step. Firstly, the force required by the protective film 4 to pick up the chips 30 is significantly reduced. Therefore, the pick-up step can be carried out easily, and the risk of mechanical damage to the chips 30 is reduced or even eliminated. Secondly, contamination of the chips 30 due to adhesive residue is reliably prevented.

[0175] In the method according to the present embodiment, the protective film 4 remains continuously attached to the wafer W during wafer processing. The same protective film 4 is used for the steps of grinding the wafer back side 6 ( Fig. 5), of dividing the wafer W into the chips 30 ( Fig. 6) and the intake of the chips 30 ( Fig. 8) is used. Therefore, no steps are required to remove the protective film 4 from the wafer W and reattach the wafer W to a different film or tape. Consequently, the processing procedure is significantly simplified. Furthermore, the reduced number of wafer handling and processing steps further minimizes the risk of wafer W damage. This approach is also particularly efficient, for example, in terms of processing time and costs.

[0176] In the method according to the present embodiment, a single-layer arrangement comprising only the protective film 4 is used. In other embodiments, structures are used in which a damping layer (not shown) is applied to the rear surface 4b of the protective film 4. Optionally, a base layer (not shown) can be applied to a rear surface of the damping layer. The damping layer and / or the base layer can have the properties, characteristics, and features described above.

Claims

[1] Method for processing a substrate (W) wherein the substrate (W) has a side (1) and a side (6) opposite the one side (1), the substrate (W) has at least one recess (7) on one side (1) or on the side (6) opposite one side (1), and The procedure includes: Provide a protective film (4); Applying the protective film (4) to the side of the substrate (W) which has the at least one recess (7), such that at least a central area of ​​a front surface (4a) of the protective film (4) is in direct contact with the side of the substrate (W) which has the at least one recess (7), so that no adhesive is present between at least the central area of ​​the front surface (4a) of the protective film (4) and the side of the substrate (W) which has the at least one recess (7); Applying pressure to the protective film (4) such that the protective film (4) enters the at least one recess (7) along at least part of a depth of the recess (7); Heating the protective film (4), wherein the pressure is applied to the protective film (4) during and / or after heating the protective film (4); and Processing one side (1) of the substrate (W) and / or the side (6) of the substrate (W) opposite one side (1). [2] Method according to claim 1, wherein the application of pressure to the protective film (4) comprises or consists of applying a vacuum to the protective film (4) during and / or after the application of the protective film (4) to the side of the substrate (W) which has the at least one recess (7). [3] Method according to claim 1 or 2, wherein the substrate (W) is a wafer having on one side (1) a component area (2) with several components (27). [4] Method according to one of the preceding claims, wherein at least one dividing line (11) is formed on one side (1) of the substrate (W) and the at least one recess (7) extends along the at least one dividing line (11). [5] Method according to one of the preceding claims, wherein the pressure is applied to the protective film (4) such that the protective film (4) enters at least one recess (7) to a depth of 3 to 500 µm, preferably 5 to 300 µm, in particular 5 to 50 pm. [6] Method according to one of the preceding claims, further comprising removing substrate material from one side (1) of the substrate (W) or from the side (6) of the substrate (W) opposite one side (1) in order to form at least one recess (7). [7] Method according to any one of the preceding claims, wherein the process includes machining the side (6) of the substrate (W) that is opposite one side (1), and The processing of the side (6) of the substrate (W) opposite one side (1) includes grinding the side (6) of the substrate (W) opposite one side (1) to adjust the substrate thickness. [8] Method according to any one of the preceding claims, wherein the protective film (4) is provided with an adhesive layer (9), the adhesive layer (9) is provided only in a circumferential region of the front surface (4a) of the protective film (4), wherein the circumferential region surrounds the central region of the front surface (4a) of the protective film (4), and the protective film (4) is applied to the side of the substrate (W) which has the at least one recess (7) in such a way that the adhesive layer (9) only comes into contact with a circumferential section of the side of the substrate (W) which has the at least one recess (7). [9] Method according to one of the preceding claims, wherein a damping layer is applied to a rear surface (4b) of the protective film (4) which is opposite its front surface (4a). [10] Method according to claim 9, wherein a base layer is applied to a rear surface of the damper layer. [11] A method according to any of the preceding claims, further comprising: Dividing the substrate (W) into several separate elements (30), and Picking up the separated elements (30) from the protective film (4). [12] Method according to any of the preceding claims, wherein the protective film (4) consists of a polymer, in particular a polyolefin. [13] Method according to one of the preceding claims, further comprising attaching a circumferential section of the protective film (4) to an annular frame (25), in particular an annular frame of semiconductor size. [14] Method according to any of the preceding claims, wherein the protective film (4) remains continuously attached to the substrate (W) during the processing of the substrate (W).

Images