Substrate processing methods

Abstract

Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), wherein a back side layer (14) is formed on the second surface (6) and the method comprises: Applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) in a state in which a focal point of the laser beam (LB) is located at a position within the substrate (2) that is closer to the second surface (6) than to the first surface (4), such that several alignment marks (16) are formed in the backside layer (14) and / or in a region of the second surface (6) where the backside layer (14) is not present, and Removal of substrate material along the at least one separation line (12) from the side of the second surface (6) by using a substrate material removal agent (26), wherein the alignment marks (16) are used to align the substrate material removal agent (26) relative to the at least one dividing line (12).

Description

Technical field

[0001] The present invention relates to a method for processing a substrate which has a first surface with at least one separating line formed thereon and a second surface which is opposite the first surface. Technical background

[0002] On substrates such as wafers, for example semiconductor wafers, electronic components such as integrated circuits (ICs), low-integration devices (LSIs), and light-emitting diodes (LEDs) are formed by providing a component area on a front surface of the substrate. The substrate can be a wafer made of, for example, silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), silicon (Si), or similar materials. The electronic components can be, for example, power semiconductor devices designed for energy-efficient products.

[0003] In a semiconductor device manufacturing process, a wafer containing a component area with multiple components separated by several parting lines (also called "roads") is divided into individual dies. This manufacturing process typically includes a cutting step to slice the wafer along the parting lines to obtain the individual dies. The wafer can be sliced ​​along the parting lines from either its front or back side.

[0004] In an optical device fabrication process, an optical device layer, consisting, for example, of an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, is formed on the front face of a single-crystal substrate, such as a sapphire, silicon carbide, or gallium nitride substrate. The optical device layer is partitioned by dividing lines to define separate regions in which optical devices, such as light-emitting diodes (LEDs) and laser diodes, are formed. By depositing the optical device layer on the front face of the single-crystal substrate, an optical device wafer is formed. The optical device wafer is then partitioned, for example, by cutting, along the dividing lines to separate the regions containing the optical devices, thus obtaining the individual optical devices as chips or dies.

[0005] In engineering, a common method for dividing such substrates is to cut the substrate from its front side, where the parting lines are formed, for example, by blade cutting or laser cutting along the parting lines. This significantly simplifies the alignment of a cutting tool relative to the parting lines. However, since the component area is also located on the front side of the substrate, the quality of the components can be compromised by the cutting process. In particular, problems such as chipping on the front and / or back side and a reduction in the die strength of the resulting chips or dies frequently occur.

[0006] To avoid these problems, it was suggested that the substrate be cut from the back side along the parting lines. However, this approach significantly complicates the alignment of the cutting tool relative to the parting lines and substantially reduces its alignment accuracy. The reduction in alignment accuracy typically has to be compensated for by widening the parting lines to increase the positioning tolerances of the cutting tool. However, such widening of the parting lines reduces the number of components that can be placed on the substrate, which impairs manufacturing efficiency and leads to a waste of substrate material. This problem is particularly pronounced in the case of expensive substrate materials such as SiC and GaAs.

[0007] The problems described above are further exacerbated if a backing layer, such as a metal layer, is present on the back of the substrate. The presence of such a backing layer typically makes it more difficult to detect the parting lines from the back of the substrate, thus further complicating the alignment of the cutting tool. In particular, the backing layer can block the transmission of light in the visible and / or infrared (IR) range. For example, if two separate cameras are used to image the substrate simultaneously from its front and back sides in order to align the cutting tool relative to the parting lines, it is very difficult to precisely align the cameras, which usually results in poor alignment accuracy.

[0008] Therefore, there remains a need for a method for processing a substrate that makes it possible to process the substrate in an accurate and efficient manner.

[0009] US patent 2015 / 0079761A1 discloses a method for cutting a wafer having a metal coating on its back side. In this method, a pattern is formed in the metal coating by applying a laser beam. Summary of the invention

[0010] Accordingly, an objective of the present invention is to provide a method for processing a substrate that enables the substrate to be processed accurately and efficiently. This objective is achieved by a substrate manufacturing method with the technical features of claim 1. Preferred embodiments of the invention are set forth in the dependent claims.

[0011] The disclosure provides a method for processing a substrate comprising a first surface with at least one parting line formed thereon and a second surface opposite the first surface. The method includes applying a protective cover to the first surface, applying a laser beam to the protective cover such that several alignment marks are formed in the protective cover, and removing substrate material along the at least one parting line from the side of the second surface using a substrate material removal agent. The alignment marks are used to align the substrate material removal agent relative to the at least one parting line. This method is not part of the claimed invention.

[0012] In the method according to the disclosure, the substrate material is removed along the at least one separation line from the side of the second surface. Therefore, it can be reliably avoided that the integrity of the first surface is compromised by the substrate material removal process. In particular, if a component area with multiple components is formed on the first surface, the risk of the components' quality being compromised by the removal of substrate material can be minimized. The occurrence of problems such as chipping on the front and / or back and a deterioration in the die strength of the resulting chips or dies can be prevented.

[0013] Furthermore, the laser beam is applied to the protective cover in such a way that the multiple alignment marks are formed within the cover. In this way, the alignment marks can be formed efficiently and with a high degree of accuracy.

[0014] The alignment marks thus formed are used to align the substrate material removal agent relative to the at least one parting line. Therefore, the substrate material removal agent can be aligned with increased accuracy relative to the at least one parting line, enabling the substrate material removal process to be carried out with a high degree of precision. Consequently, the width of the at least one parting line can be reduced, allowing for the placement of an increased number of elements, such as components, on the first substrate surface. In this way, manufacturing efficiency is significantly increased and substrate material waste is avoided. This is particularly advantageous in the case of expensive substrate materials, such as SiC and GaAs.

[0015] Therefore, the processing method according to the disclosure makes it possible to process the substrate in an accurate and efficient manner.

[0016] The laser beam applied to the protective cover in such a way as to form the multiple alignment marks in the protective cover can be a pulsed laser beam. The pulsed laser beam can have a pulse width that is, for example, in the range of 1 fs to 300 ns.

[0017] The laser beam can be applied to the protective cover in such a way that the multiple alignment marks are formed within the cover after it has been attached to the first surface. This further increases the accuracy of the alignment marks' placement within the protective cover relative to at least one dividing line.

[0018] The laser beam can be applied to the protective cover from the side of the first surface of the substrate.

[0019] The shapes and arrangement of the alignment markers are not particularly restricted. For example, all or some of the alignment markers can be in the form of one or more points or one or more lines, such as curved and / or straight lines.

[0020] Several parting lines may be formed on the first surface of the substrate. The method may involve removing substrate material along one or more, preferably all, of the parting lines by using the substrate material removal agent. In this case, the alignment marks are used to align the substrate material removal agent relative to the parting line or lines along which the substrate material is to be removed.

[0021] A component area with multiple components can be formed on the first surface of the substrate. The components can be separated by at least one dividing line. The component area can include components such as electronic components, semiconductor components (e.g., power semiconductor components, especially energy-efficient power semiconductor components), or the like. The components can include, for example, transistors (e.g., MOSFETs, such as SiC MOSFETs, or insulated-gate bipolar transistors (IGBTs)), or diodes (e.g., Schottky barrier diodes).

[0022] The protective cover can be attached to the first surface of the substrate in such a way that the components formed in the component area are covered. The protective cover can protect the first substrate surface, in particular the components formed in the component area, from contamination and / or damage, for example.

[0023] The substrate can consist of, for example, a semiconductor, glass, sapphire (Al₂O₃), a ceramic such as an aluminum oxide ceramic, quartz, zirconium oxide, PZT (lead zirconate titanate), a polycarbonate, an optical crystal material, or the like. The substrate can be a wafer, such as a semiconductor wafer.

[0024] In particular, the substrate can consist 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), silicon dioxide (SiO2), or the like. The substrate is particularly preferably composed of SiC.

[0025] The substrate can be a single-crystal substrate, a glass substrate, a compound substrate, such as a compound semiconductor substrate, for example a SiC, GaAs or GaN substrate, or a polycrystalline substrate, such as a ceramic substrate.

[0026] The width of at least one dividing line can be 1 µm or less. The width of at least one dividing line can be in the range of 1 µm to 200 µm, in the range of 10 µm to 100 µm, or in the range of 10 µm to 50 µm.

[0027] A section of the protective cover may extend laterally or radially beyond the first surface of the substrate. The lateral or radial directions of the substrate are perpendicular to its thickness direction. The thickness direction of the substrate extends from the first substrate surface to the second substrate surface. The section of the protective cover that extends laterally or radially beyond the first surface of the substrate may surround, in particular completely surround, the first surface of the substrate.

[0028] The protective cover section can extend laterally or radially beyond the first surface of the substrate by, for example, 10 µm to 1000 µm, or by 1000 µm or more. The protective cover section can also extend laterally or radially beyond an outer edge of the substrate by, for example, 10 µm to 1000 µm, or by 1000 µm or more.

[0029] At least one, preferably several, or particularly preferably all of the alignment marks can be formed in the section of the protective cover that extends laterally or radially beyond the first surface. In this way, the substrate material removal agent can be aligned with particularly high accuracy relative to the at least one parting line, thus enabling the substrate material removal process to be carried out with a particularly high degree of precision.

[0030] The portion of the protective cover that extends laterally or radially beyond the first surface can extend along the thickness direction of the substrate from the first surface towards the second surface. The portion of the protective cover that extends laterally or radially beyond the first surface can extend along 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 from the first surface towards the second surface. The portion of the protective cover that extends laterally or radially beyond the first surface can extend substantially along the entire thickness of the substrate from the first surface towards the second surface.

[0031] At least one, preferably several, or particularly preferably all of the alignment marks can be formed in the section of the protective cover that extends laterally or radially beyond the first surface, in a position closer to the second surface than to the first surface. In this way, the alignment accuracy with which the substrate material removal agent can be aligned relative to the least one parting line can be further increased.

[0032] The at least one, preferably some, or particularly preferably all of the alignment marks can be formed in the section of the protective cover that extends laterally or radially beyond the first surface in a position where the ratio of a second distance between the position and the second surface in the substrate thickness direction to a first distance between the position and the first surface in the substrate thickness direction is 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. The at least one, preferably some, or particularly preferably all of the alignment marks can be formed in a position that is located at least substantially on the second surface of the substrate.

[0033] A backsheet can be formed on the second surface of the substrate. The backsheet can be a conductive layer. For example, the backsheet can be a metal layer. The backsheet can be made of a material, such as a metal, that is at least substantially opaque to light in the visible and / or infrared (IR) range.

[0034] In the method according to the present disclosure, the alignment marks formed in the protective cover are used to align the substrate material removal agent relative to the at least one parting line. Therefore, the alignment process is not affected by the presence of the back layer and can thus be carried out with a high degree of accuracy. For this reason, the method is particularly advantageous for processing substrates with a back layer, such as a metal layer, on the second substrate surface.

[0035] The backing layer, such as a metal layer, can cover at least the essential part of the substrate's secondary surface. Even in this case, the substrate material removal agent can be reliably and accurately aligned relative to at least one separation line by using the alignment marks in the protective cover.

[0036] The back layer, such as a metal layer, can cover only a portion of the substrate's second surface. Specifically, the back layer can be present only in a central section of the second surface. In this case, the back layer cannot be present in an outer or circumferential section of the second surface that surrounds, i.e., completely encircles, the central section. The outer or circumferential section of the second surface can have a width, for example, a ring width, ranging from 0.1 mm to 3 mm. The back layer can be present only in a region of the second surface that corresponds to the component area formed on the first surface. The substrate can have a circumferential edge region on the first surface that does not contain any components and is formed around, i.e., encircling, the component area.The back layer can be arranged such that it is not located in an area of ​​the second surface that corresponds to the perimeter boundary area of ​​the first surface.

[0037] The protective cover may include or consist of a protective film.

[0038] The protective film can be applied to the first surface in such a way that the entire front surface of the protective film is in direct contact with the first surface. In this case, there is no material, in particular no adhesive, between the front surface of the protective film and the first surface.

[0039] Therefore, the risk of possible contamination or damage to the first surface, for example due to the adhesive force of an adhesive layer or adhesive residues on the substrate, can be reliably eliminated.

[0040] The protective film can be applied to the first surface by applying an external impulse to the protective film during and / or after its application to the first surface. Applying the external impulse to the protective film may include or consist of heating and / or cooling the protective film, applying a vacuum to the protective film, and / or irradiating the protective film with radiation, such as light, for example, using a laser beam. The external impulse may also include or consist of a chemical reaction, electron or plasma irradiation, mechanical treatment such as pressure, friction, or the application of ultrasound, and / or static electricity.

[0041] Alternatively or additionally, the protective film can be provided with an adhesive layer. This adhesive layer is applied only to a circumferential region of the protective film's front surface, and this circumferential region surrounds a central region of the protective film's front surface. In this case, no adhesive is present in the central region of the protective film's front surface. Within this central region, the protective film's front surface and the first surface can be in direct contact. The protective film can be applied to the first surface in such a way that the adhesive layer only comes into contact with a circumferential section of the first surface. This circumferential section of the first surface, with which the adhesive layer comes into contact, could, for example, be the perimeter edge of the first surface, where no components are present.

[0042] Therefore, the risk of possible contamination or damage to the first surface, for example due to the adhesive strength of the adhesive layer or adhesive residues on the substrate, can be significantly reduced or even eliminated.

[0043] The protective film can consist of a single material, in particular a single homogeneous material.

[0044] The protective film can be made of a plastic material, such as a polymer. For example, the protective film can be made of a polyolefin. In particular, the protective film can be made of polyethylene (PE), polypropylene (PP), or polybutylene (PB).

[0045] 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.

[0046] 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.

[0047] The protective cover may include or consist of a damping layer. The protective cover may include or consist of both the protective film and the damping layer.

[0048] The damping layer can be applied to a rear surface of the protective film that faces its front surface. If the damping layer is applied to the rear surface of the protective film, any protrusions extending from the front surface along the thickness direction of the substrate can be embedded in the damping layer.

[0049] The protective cover, in particular the protective cover that includes or consists of the damping layer, can serve as a support for holding the substrate during the removal of substrate material along the at least one separation line from the side of the second surface by using the substrate material removal agent. In this way, unwanted displacement of the substrate or of elements obtained from the substrate, such as chips or dies, can be reliably prevented.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The protective cover can include or consist of a base layer. The protective cover can include or consist of the damping layer and the base layer. The protective cover can include or consist of the protective film, the damping layer, and the base layer.

[0055] The base layer can be applied to the rear surface of the damping layer, which is opposite its front surface, which is attached to the protective film.

[0056] 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.

[0057] 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).

[0058] Furthermore, the base layer can be made from a combination of the materials listed above.

[0059] 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.

[0060] 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.

[0061] A front surface of the base layer can be in contact with the rear surface of the damper layer, and a rear surface of the base layer opposite its front surface can be substantially parallel to the second surface of the substrate. Therefore, when substrate material is removed along the at least one parting line from the side of the second surface by using the substrate material removal agent, suitable counter-pressure can be exerted on the rear surface of the base layer, for example by placing this rear surface on a clamping table.

[0062] The protective cover can be made of a material that is transparent to the laser beam, i.e., the laser beam applied in such a way that the multiple alignment marks are formed in the protective cover. The protective film can be made of a material that is transparent to the laser beam. The damping layer can be made of a material that is transparent to the laser beam. The base layer can be made of a material that is transparent to the laser beam.

[0063] The laser beam can be applied to the protective cover in such a way that one, some or all of the multiple alignment marks are formed in the protective film and / or the damping layer and / or the base layer.

[0064] The section of the protective cover that extends laterally or radially beyond the first surface and along the thickness direction of the substrate from the first surface towards the second surface may at least substantially be a section of the damping layer.

[0065] The invention provides a method for processing a substrate comprising a first surface with at least one dividing line formed thereon and a second surface opposite the first surface, wherein a backing layer is formed on the second surface. The method comprises applying a laser beam to the substrate from the side of the first surface, wherein the substrate consists of a material that is transparent to the laser beam, and the laser beam is applied to the substrate in a state in which a focal point of the laser beam is located at a position within the substrate that is closer to the second surface than to the first surface, such that several alignment marks are formed in the backing layer and / or in a region of the second surface where the backing layer is not present.The method further comprises removing substrate material along the at least one separation line from the side of the second surface by using a substrate material removal agent. The alignment marks are used to align the substrate material removal agent relative to the at least one separation line.

[0066] The substrate, the at least one dividing line, the backing layer and the alignment marks may have the same features, properties and characteristics described above.

[0067] In the method according to the invention, the substrate material is removed along at least one separation line from the side of the second surface. Therefore, it can be reliably avoided that the integrity of the first surface is compromised by the substrate material removal process. In particular, if a component area with multiple components is formed on the first surface, the risk of the components' quality being compromised by removing substrate material can be minimized. The occurrence of problems such as chipping on the front and / or back side and a deterioration in the die strength of the resulting chips or dies can be prevented.

[0068] Furthermore, the laser beam is applied to the substrate in a state where the focal point of the laser beam is located within the substrate closer to the second surface than to the first surface, so that the multiple alignment marks are formed in the back layer and / or in a region of the second surface where the back layer is absent. In this way, the alignment marks can be formed efficiently and with a high degree of accuracy. In particular, by positioning the focal point of the laser beam closer to the second surface than to the first surface, it can be reliably ensured that the alignment marks are clearly visible from the side of the second surface.

[0069] The alignment marks thus formed are used to align the substrate material removal agent relative to the at least one parting line. Therefore, the substrate material removal agent can be aligned with increased accuracy relative to the at least one parting line, enabling the substrate material removal process to be carried out with a high degree of precision. Consequently, the width of the at least one parting line can be reduced, allowing for the placement of an increased number of elements, such as components, on the first substrate surface. This significantly increases manufacturing efficiency and avoids substrate material waste. This is particularly advantageous in the case of expensive substrate materials, such as SiC and GaAs.

[0070] Therefore, the machining method according to the invention makes it possible to machine the substrate in a precise and efficient manner.

[0071] The focal point of the laser beam can be located at a position within the substrate where the ratio of the second distance between the position and the second surface in the substrate thickness direction to the first distance between the position and the first surface in the substrate thickness direction is 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. The focal point of the laser beam can be located at a position within the substrate that is situated at least substantially on the second surface of the substrate. The focal point of the laser beam can be located at a position within the substrate that is situated at least substantially on an interface between the second surface of the substrate and the back-side layer.

[0072] Since the focal point of the laser beam is located within the substrate closer to the second surface than to the first, a significant portion of the laser beam is absorbed at and / or near the second substrate surface, for example, at and / or near the interface between the second substrate surface and the backsheet. Therefore, the alignment marks can be formed efficiently and with a high degree of accuracy, particularly so that they are clearly visible from the side of the second surface. For example, the alignment marks can be formed in the backsheet by at least partially melting it.

[0073] The laser beam, which is applied to the substrate in such a way as to form the multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is absent, can be a pulsed laser beam. The pulsed laser beam can have a pulse width that is, for example, in the range of 1 fs to 300 ns.

[0074] The shapes and arrangement of the alignment marks are not particularly restricted. For example, all or some of the alignment marks can be in the form of one or more dots or one or more lines, such as curved and / or straight lines.

[0075] Several parting lines may be formed on the first surface of the substrate. The method may involve removing substrate material along one or more, preferably all, of the parting lines by using the substrate material removal agent. In this case, the alignment marks are used to align the substrate material removal agent relative to the parting line or lines along which the substrate material is to be removed.

[0076] A component area with multiple components can be formed on the first surface of the substrate. The components can be separated by at least one dividing line. The component area can include components such as electronic components, semiconductor components (e.g., power semiconductor components, especially energy-efficient power semiconductor components), or the like. The components can include, for example, transistors (e.g., MOSFETs, such as SiC MOSFETs, or insulated-gate bipolar transistors (IGBTs)), or diodes (e.g., Schottky barrier diodes).

[0077] The back layer can be a conductive layer. For example, the back layer can be a metal layer. The back layer can be made of a material, such as a metal, that is at least substantially opaque to light in the visible and / or infrared (IR) range.

[0078] In the method according to the present invention, the alignment marks formed in the back layer and / or in a region of the second surface where the back layer is absent are used to align the substrate material removal agent relative to the at least one parting line. Therefore, the alignment process is not affected by the presence of the back layer and can thus be carried out with a high degree of accuracy.

[0079] The backing layer, such as a metal layer, can cover at least substantially the entire second surface of the substrate. If the backing layer covers the entire second substrate surface, all alignment marks are formed in the backing layer. In this case, the substrate material removal agent can be reliably and accurately aligned relative to the at least one separation line by using the alignment marks in the backing layer.

[0080] The back layer, such as a metal layer, can cover only a portion of the substrate's second surface. Specifically, the back layer can be present only in a central section of the second surface. In this case, the back layer cannot be present in an outer or circumferential section of the second surface that surrounds, i.e., completely encircles, the central section. The back layer can only be present in a region of the second surface that corresponds to the component area formed on the first surface.

[0081] The substrate can have a peripheral edge region on the first surface that contains no components and is formed around the component region, i.e., in such a way that it surrounds it. The back layer can be arranged such that it is not located in a region of the second surface that corresponds to the peripheral edge region of the first surface.

[0082] If the backing layer covers only a portion of the second substrate surface, all alignment marks can be formed in the backing layer, all alignment marks can be formed in the area of ​​the second surface where the backing layer is absent, or some of the alignment marks can be formed in the backing layer and some of the alignment marks in the area of ​​the second surface where the backing layer is absent. In each of these cases, the substrate material removal agent can be reliably and accurately aligned relative to the at least one separation line using the alignment marks.

[0083] The method can further include applying a protective cover to the first surface. The protective cover can be made of a material that is transparent to the laser beam, i.e., the laser beam that is applied to the substrate in such a way as to form multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is absent. The protective cover can be applied to the first surface before the laser beam is applied to the substrate. The laser beam can be applied to the substrate through the protective cover, i.e., in such a way that the laser beam is transmitted through the protective cover.

[0084] The protective cover can be attached to the first surface of the substrate in such a way that the components formed in the component area are covered. The protective cover can protect the first substrate surface, in particular the components formed in the component area, from contamination and / or damage, for example.

[0085] The protective cover may have the same features, properties, and characteristics described above. In particular, the protective cover may include or consist of the protective film and / or the damping layer and / or the base layer, as described above.

[0086] The methods according to the invention can further comprise applying a laser beam to the substrate from the side of the first surface, wherein the substrate consists of a material that is transparent to the laser beam, and the laser beam is applied to the substrate at least at several positions along the at least one dividing line in such a way that several modified areas are formed in the substrate.

[0087] The laser beam, which is applied to the substrate in such a way as to form the multiple modified areas in the substrate, can be a pulsed laser beam. The pulsed laser beam can have a pulse width that is, for example, in the range of 1 fs to 300 ns.

[0088] The laser beam applied to the substrate to form the multiple modified areas in the substrate can be the same laser beam as the laser beam applied to the protective cover to form the multiple alignment marks in the protective cover, or a different laser beam.

[0089] The laser beam applied to the substrate in such a way as to form the multiple modified areas in the substrate can be the same laser beam as the laser beam applied to the substrate in such a way as to form the multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is not present, or a different laser beam.

[0090] The laser beam for forming the multiple modified areas in the substrate can be applied to the substrate after the laser beam for forming the multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is absent has been applied to the substrate. This ensures that the alignment marks are formed with a particularly high degree of accuracy. In particular, it reliably prevents the modified areas formed in the substrate from interfering with the process of applying the laser beam for forming the multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is absent.

[0091] Alternatively, the laser beam can be applied to the substrate to form the multiple modified areas before the laser beam is applied to the substrate to form the multiple alignment marks in the back layer and / or in an area of ​​the second surface where the back layer is not present.

[0092] The laser beam for forming the multiple modified areas in the substrate can be applied to the substrate after the laser beam for forming the multiple alignment marks in the protective cover has been applied to the protective cover.

[0093] Alternatively, the laser beam can be applied to the substrate to form the multiple modified areas in the substrate before the laser beam is applied to the protective cover to form the multiple alignment marks in the protective cover.

[0094] If multiple separation lines are formed on the first substrate surface, the method can include applying the laser beam from the side of the first surface to the substrate at least at several positions along one or more, preferably all, of the separation lines. In this case, several modified areas are formed in the substrate at least at several positions along the one or more, preferably all, of the separation lines.

[0095] The laser beam can be applied to the substrate at least at several positions along the at least one dividing line in a state where a focal point of the laser beam is located at a distance from the first surface in the direction from the first surface to the second surface. Alternatively, the laser beam can be applied to the substrate at least at several positions along the at least one dividing line in a state where the focal point of the laser beam is located at a distance from the first surface in the direction opposite to the direction from the first surface to the second surface.

[0096] Each modified region can be located entirely within the substrate body. In this case, the modified regions do not extend to the first surface, nor do they extend to the second surface. Alternatively, at least one, some, or all of the modified regions can extend to the first and / or second surface.

[0097] The modified region is an area of ​​the substrate that has been modified by the application of the laser beam, such as a pulsed laser beam. For example, the modified region could be an area of ​​the substrate where the structure of the substrate material has been modified by the application of the laser beam.

[0098] The modified region can include or be an amorphous region or a region in which cracks have formed. The modified region can include or consist of a space, for example a cavity, within the substrate material, with the space being surrounded by an amorphous region or a region in which cracks have formed.

[0099] If the modified area includes or is an area where cracks have formed, these cracks may be microcracks. The cracks may have dimensions, such as lengths and / or widths, in the micrometer range. For example, the cracks may have widths ranging from 0.1 µm to 100 µm and / or lengths ranging from 1 µm to 1000 µm.

[0100] The multiple modified areas can be formed in the substrate such that the distance between the centers of adjacent modified areas in the extension direction of the at least one dividing line is in the range of 0.1 µm to 50 µm, preferably 0.1 µm to 30 µm and more preferably 0.1 µm to 15 µm.

[0101] The modified areas can be equidistant from each other in the direction of extension of the at least one dividing line. Alternatively, some or all adjacent or neighboring modified areas can have different distances from each other in the direction of extension of the at least one dividing line.

[0102] The modified areas can have diameters ranging from 0.1 µm to 30 µm, preferably 0.1 µm to 20 µm and more preferably 0.1 µm to 10 µm.

[0103] The multiple modified areas can be formed in the substrate in such a way that adjacent or neighboring modified areas do not overlap. This ensures with particular reliability that the substrate retains a sufficient degree of strength or robustness to allow for its efficient further handling and / or processing, especially in the step of removing substrate material along the at least one dividing line.

[0104] The distance between the outer edges of adjacent or neighboring modified areas in the width direction of the at least one dividing line and / or in the extension direction of the at least one dividing line can be at least 1 µm.

[0105] The multiple modified areas can be formed in the substrate in such a way that adjacent or neighboring modified areas overlap each other, for example in the lateral direction of the at least one dividing line and / or in the longitudinal direction of the at least one dividing line, at least partially.

[0106] The modified areas can be configured to extend only along a portion of the substrate thickness in the direction from the first surface to the second surface. Some or all of the modified areas can be configured to extend along 5% or more and 60% or less, preferably 10% or more and 40% or less, and more preferably 15% or more and 30% or less of the substrate thickness.

[0107] Forming the modified areas with a large extent along the thickness of the substrate is particularly preferred with regard to extending the service life of the substrate material removal device, in particular a blade or a saw.

[0108] The extent of some or all of the modified areas along the thickness of the substrate can be chosen appropriately, for example depending on whether it is intended to completely or partially remove substrate material along the thickness of the substrate, for example by completely or partially cutting the substrate along its thickness.

[0109] The extent of the modified areas along the thickness of the substrate and the position of the modified areas along the thickness of the substrate can be precisely controlled, for example by positioning the focal point of the laser beam at a suitable distance from the first surface, for example in the direction from the first surface towards the second surface.

[0110] In some embodiments of the present invention, several modified regions, for example two or more, three or more, four or more, five or more, or six or more modified regions, can be formed at each of the several positions along the at least one dividing line where the laser beam is applied, and the several modified regions can be arranged side by side along the direction from the first surface to the second surface, that is, along the thickness direction of the substrate. In this way, several layers of modified regions can be formed, with the several layers being arranged one above the other along the thickness direction of the substrate. Such an arrangement of layers of modified regions can extend over 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the thickness of the substrate.

[0111] In the methods according to the invention, the substrate material can be mechanically removed along the at least one separation line. In particular, the substrate material can be removed by mechanically cutting the substrate along the at least one separation line.

[0112] The substrate material can be removed by cutting the substrate along at least one separation line. For example, the substrate can be cut using a mechanical cutting device, such as a blade or a saw, as the substrate material removal device. The substrate material can also be removed by laser cutting, particularly laser ablation, using a laser cutting device as the substrate material removal device. Finally, the substrate material can be removed by plasma cutting, for example, using a plasma source or the like as the substrate material removal device. Cutting the substrate is a particularly efficient, simple, and reliable way to remove the substrate material along at least one separation line.

[0113] Forming multiple modified areas in the substrate along the at least one separation line reduces the substrate's strength in the areas where the modified areas are formed. Therefore, the removal of substrate material along the at least one separation line can be significantly facilitated by forming such modified areas in the substrate. In particular, the mechanical removal of substrate material, such as mechanical cutting of the substrate, along the at least one separation line can be carried out more efficiently, for example, with an increased processing speed. For instance, in the case of a blade or saw cutting operation, the blade or saw cutting speed can be significantly increased.In the methods according to the invention, the substrate material can be removed only along a portion of the substrate thickness in the direction from the second surface to the first surface. The substrate material can be removed along 30% or more, preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, and even more preferably 70% or more of the substrate thickness.

[0114] The substrate material can be removed along the entire thickness of the substrate. In this way, the substrate is divided along at least one dividing line by the substrate material removal process.

[0115] The substrate material can be removed along the entire extent of the modified areas in the direction from the second surface to the first surface, or only along a portion of this extent. Removing the substrate material along the entire extent of the modified areas can further increase the die strength of elements obtained from the substrate, such as chips or dies. The substrate material can be removed along 30% or more, preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, and even more preferably 70% or more of the extent of the modified areas.

[0116] The methods according to the invention may further include applying an external force to the substrate after removing substrate material along the at least one dividing line, in order to divide the substrate along the at least one dividing line.

[0117] For example, external force can be applied to the substrate by radially expanding the protective cover, that is, by using the protective cover as an expansion strip. Alternatively, for example, if no protective cover is used, an expansion strip can be attached to the first substrate surface. Subsequently, the substrate can be divided by radially expanding the expansion strip along at least one dividing line. Brief description of the drawings

[0118] Non-limiting examples of the invention are discussed below with reference to the drawings, wherein: Fig. 1 a cross-sectional representation showing a wafer as a substrate to be processed by embodiments of the methods according to the present invention; Fig. 2 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to a first embodiment of the method of the present invention; Fig. 3 is a cross-sectional representation that shows the result of the in Fig. 2 illustrated steps of applying the laser beam to the substrate; Fig. 4 is a cross-sectional representation showing the result of a step of attaching the substrate to a cover according to the first embodiment of the method of the present invention; Fig. 5 is a cross-sectional representation illustrating one step of cutting the substrate according to the first embodiment of the method of the present invention; Fig. 6 is a cross-sectional representation that shows the result of the in Fig. 5 illustrated steps of cutting the substrate are shown; Fig. 7 is a cross-sectional representation showing the result of a step of applying an external force to the substrate according to the first embodiment of the method of the present invention; Fig. 8 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to a second embodiment of the method of the present invention; Fig. 9 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to a modification of the second embodiment of the method of the present invention; Fig. 10 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to a third embodiment of the method of the present invention; Fig. 11 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to a modification of the third embodiment of the method of the present invention; Fig. 12 is a cross-sectional representation showing the result of a step of applying a protective cover to the substrate according to a fourth embodiment of the method of the present disclosure; Fig. 13 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to the fourth embodiment of the method of the present disclosure; Fig. 14 is a cross-sectional representation showing the result of a step of applying the substrate to a cover and illustrating a step of cutting the substrate according to the fourth embodiment of the method of the present disclosure; Fig. 15 is a cross-sectional representation showing the result of a step of applying a protective cover to the substrate according to a modification of the fourth embodiment of the method of the present disclosure; Fig. 16 is a cross-sectional representation illustrating one step of applying a laser beam to the substrate according to the modification of the fourth embodiment of the method of the present disclosure; Fig. 17 is a cross-sectional representation illustrating one step of cutting the substrate according to the modification of the fourth embodiment of the method of the present disclosure; Fig. 18 is a cross-sectional representation showing the result of a step of applying a protective cover to the substrate according to a fifth embodiment of the method of the present disclosure; Fig. 19 is a cross-sectional view illustrating one step of applying a laser beam to the substrate according to the fifth embodiment of the method of the present disclosure; and Fig. Figure 20 is a cross-sectional representation illustrating one step of cutting the substrate according to the fifth embodiment of the method of the present disclosure. Detailed description of preferred embodiments

[0119] Preferred embodiments of the present invention are described below with reference to the accompanying drawings. The preferred embodiments relate to methods for processing a wafer as a substrate.

[0120] Fig. Figure 1 is a cross-sectional view of a substrate 2 to be processed by the embodiments of the methods of the present invention. The substrate 2 is a semiconductor wafer, in particular a SiC wafer. However, different types of substrate and, in particular, different substrate materials can be used, as described in more detail above.

[0121] As in Fig. As shown in Figure 1, the substrate 2 has a first surface 4 and a second surface 6 opposite the first surface 4. The first surface 4 and the second surface 6 are essentially parallel to each other. A component area 8 with several components 10 is formed on the first surface 4.

[0122] The components 10 are separated by several dividing lines 12, which are also formed on the first surface 4. The dividing lines 12 are essentially arranged in a grid pattern. The components 10 can, for example, include or be transistors, such as MOSFETs or insulated-gate bipolar transistors (IGBTs), or diodes, such as Schottky barrier diodes.

[0123] A backside layer 14 is formed on the second surface 6. The backside layer 14 is a metal layer that is at least substantially opaque to light in the visible and infrared (IR) ranges. The backside layer 14 covers almost the entire second surface 6, with the exception of a small circumferential section of the second surface 6 (see Fig. 1).

[0124] In the following, a first embodiment of the method of the present invention is described with reference to Fig. 2 to 7 described.

[0125] A pulsed laser beam LB is applied to the substrate 2 from the side of the first surface 4, as shown in Fig. 2 is indicated by an arrow. The pulsed laser beam LB can have a pulse width, for example, in the range of 1 fs to 300 ns. The material of the substrate 2, in particular SiC, is transparent to the pulsed laser beam LB, so that the pulsed laser beam LB is transmitted through the substrate 2. The pulsed laser beam LB is applied to the substrate 2 in a state in which a focal point of the pulsed laser beam LB is located at a position that is at least substantially at an interface between the second surface 6 of the substrate 2 and the back side layer 14. This arrangement of the focal point is described in Fig. 2 not illustrated. By arranging the focal point at least substantially at the interface between the second surface 6 of the substrate 2 and the backside layer 14, a significant portion of the pulsed laser beam LB is absorbed at this interface, thereby at least partially melting the backside layer 14. In this way, an alignment mark 16 is formed in the backside layer 14 (see Fig. 2) Subsequently, the focal point of the pulsed laser beam LB is moved laterally along the substrate 2 to form further alignment marks 16 at different positions in the backside layer 14. By using the pulsed laser beam LB in this manner, multiple alignment marks 16 can be formed efficiently and with a high degree of accuracy in the backside layer 14, in particular so that they are clearly visible from the side of the second surface 6.

[0126] For example, the pulsed laser beam LB applied to form the multiple alignment marks 16 on the substrate 2 can have the following properties: Wellenlänge: 300 bis 1100 nm, Pulsbreite: 10 bis 100 ns, Pulsenergie: 1 bis 10 µJ, Pulsabstand (Mi.bis Mittelpunkt): 0,5 bis 4 µm

[0127] In the first embodiment, the alignment marks 16 are provided such that at least one alignment mark 16 is arranged substantially at the center of each dividing line 12 in the width direction (see Fig. 3) The alignment markers 16 can, for example, be in the form of one or more points or one or more lines. However, the shapes and arrangement of the alignment markers 16 are not particularly restricted, as described in more detail above.

[0128] After forming the alignment marks 16 in the back side layer 14, the pulsed laser beam LB is applied to the substrate 2 from the side of the first surface 4 at several positions along each dividing line 12 such that several modified areas 18 are formed in the substrate 2 (see Fig. 2 and Fig. 3) The pulsed laser beam LB applied to the substrate 2 to form the multiple modified areas 18 can be the same as the pulsed laser beam LB applied to the substrate 2 to form the multiple alignment marks 16. Alternatively, two different laser beams can be used for these purposes.

[0129] For example, the pulsed laser beam LB applied to the substrate 2 to form the several modified areas 18 can have the following properties: Wellenlänge: 300 bis 1100 nm, Pulsbreite: 10 bis 100 ns, Pulsenergie: 5 bis 40 µJ, Pulsabstand (Miittelpunkt bis Mittelpunkt): 6 bis 24 µm.

[0130] By forming the modified areas 18 after forming the alignment marks 16, it can be ensured that the alignment marks 16 are formed with a particularly high degree of accuracy. In particular, it can be reliably prevented that the modified areas 18 interfere with the process of applying the pulsed laser beam LB to form the alignment marks 16.

[0131] The modified regions 18 are regions of the substrate 2 that have been modified by the application of the pulsed laser beam LB. For example, the modified regions 18 may include or be amorphous regions and / or regions in which cracks have formed. The cracks may have dimensions, such as lengths and / or widths, in the µm range, as described in more detail above.

[0132] In the present embodiment, each modified area 18 is arranged completely within the body of the substrate 2, as shown in Fig. 2 and Fig. Figure 3 shows that each modified region 18 extends only along a portion of the substrate 2 thickness in the direction from the first surface 4 to the second surface 6. The extent of the modified regions 18 along the substrate thickness and their position along the substrate thickness can be precisely controlled, for example, by positioning the focal point of the pulsed laser beam LB at a suitable distance from the first surface 4.

[0133] As in Fig. 2 and Fig. As shown in Figure 3, at each of the several positions along the dividing lines 12, several, namely three, modified regions 18 are formed, and the modified regions 18 are arranged side by side along the thickness direction of the substrate 2. In this way, several layers of modified regions 18 are formed, arranged one above the other along the substrate thickness. However, the number, arrangement, extent, and shapes of the modified regions 18 are not particularly restricted.

[0134] The formation of the modified areas 18 in the substrate 2 reduces the strength of the substrate 2 in the areas where the modified areas 18 are formed. Therefore, the removal of substrate material along the parting lines 12, which is described in more detail below, can be significantly facilitated. In particular, the mechanical removal of substrate material, such as mechanical cutting of the substrate 2, along the parting lines 12 can be carried out more efficiently, for example, with an increased processing speed. In the case of a blade or saw cutting operation, the blade or saw cutting speed can be significantly increased.

[0135] In the present embodiment, although all modified areas 18 are arranged completely within the substrate 2, cracks 20 extend from the modified areas 18, particularly towards the first surface 4. As in Fig. 2 and Fig. As shown in Figure 3, the cracks 20 can optionally extend to the first surface 4. These cracks 20 in the substrate 2 are caused by the modification of the substrate material in the modified areas 18. The presence of the cracks 20 further facilitates the process of separating the substrate 2 along the separation lines 12, as described in more detail below.

[0136] After all alignment marks 16 and modified areas 18 have been formed (see Fig. 3) The substrate 2 is attached to a cover 22. In particular, the first surface 4 of the substrate 2 is attached to the cover 22 such that the cover 22 covers the components 10 formed in the component area 8 (see Fig. 4) The cover 22 can be a conventional dividing strip or the protective cover described in more detail above. For example, the cover 22 can comprise or consist of a protective film and / or a damping layer and / or a base layer, as described in more detail above. The cover 22 is held at a circumferential section thereof by an annular frame 24 such that an inner opening of the annular frame 24 is closed by the cover 22.

[0137] The cover 22 can be provided with an adhesive layer (not shown) for attaching the cover 22 to the first surface 4 of the substrate 2. The adhesive layer can be arranged only in a circumferential region of the front surface of the cover 22. In this case, the front surface of the cover 22 and the first surface 4 are in direct contact with each other in a central region of the front surface of the cover 22. Thus, the risk of possible contamination or damage to the first surface 4, in particular to the components 10, for example due to the adhesive force of the adhesive layer or adhesive residues on the substrate 2, can be significantly reduced or even eliminated.

[0138] After the substrate 2 is attached to the cover 22, substrate material is removed from the side of the second surface 6 of the substrate 2 along the dividing lines 12, as shown in Fig. Figure 5 illustrates this. The substrate material is removed by mechanically cutting the substrate 2 along the parting lines 12 using a cutting blade 26 as a substrate material removal means. Alternatively, the substrate material can be removed, for example, by laser cutting, in particular by laser ablation, using a laser cutting means as the substrate material removal means. The substrate 2 is cut through the back layer 14 along the parting lines 12 (see Figure 5). Fig. 5). Thus, the alignment marks 16 are removed during the cutting process.

[0139] Substrate 2 can be cut by a single cut or by a step cut, for example, using a combination of different cutting operations, such as cutting steps that employ cutting blades with different cutting widths. The process of cutting substrate 2 is considerably facilitated by the presence of the modified areas 18, as described in more detail above.

[0140] The alignment marks 16 formed in the back layer 14 are used to align the cutting blade 26 relative to the parting lines 12 to be cut. Therefore, the cutting blade 26 can be aligned with increased accuracy relative to the parting lines 12, enabling the substrate cutting process to be carried out with a high degree of precision. Consequently, the width of the parting lines 12 can be reduced, allowing for the placement of an increased number of components 10 on the first surface 4. This significantly increases manufacturing efficiency and avoids the waste of substrate material. This is particularly advantageous in the case of expensive substrate materials such as SiC and GaAs.

[0141] As in Fig. As shown in Figure 5, the substrate 2 is cut only along a portion of its thickness. Specifically, the substrate 2 is cut along the entire extent of the modified regions 18 in the direction from the second surface 6 to the first surface 4. In this way, the modified regions 18 are removed during the substrate cutting process. Therefore, the die strength of the dies to be obtained from the substrate 2 (see Figure 5) can be reduced by the following measure: Fig. 7) be increased further.

[0142] A force exerted on the substrate 2 by the cutting blade 26 during the substrate cutting process can promote the propagation of the cracks 20. For example, this force can cause some of the cracks 20 to extend to the first surface 4. In this way, the process of dividing the substrate 2 along the separation lines 12 can be further facilitated.

[0143] After the substrate 2 was cut along all dividing lines 12, as in Fig. As shown in Figure 6, the cover 22 is radially expanded, for example by using an expansion drum or the like. In this way, a radial external force is applied to the substrate 2 such that the substrate 2 is divided along the dividing lines 12 into individual dies 28 (see Figure 6). Fig. 7) In particular, the substrate 2 is divided along the separation lines 12, where the strength of the substrate 2 is reduced by the presence of the partial cuts formed in the substrate cutting step. The process of dividing the substrate 2 is further facilitated if the substrate 2 is further weakened along the separation lines 12 by cracks 20 extending towards the first surface 4, in particular up to the first surface 4.

[0144] After the substrate 2 has been completely divided in this way, the individual dies 28 can be picked up from the cover 22, for example by using a pickup device (not shown).

[0145] Since, in the method of the present embodiment, the substrate 2 is only cut along a portion of its thickness and completely divided by applying an external force, the widths of the dividing lines 12 can be reduced even further. In particular, these widths can be selected to be smaller than the cutting width of the dividing blade 26. For example, the dividing line widths can be 30 µm or less, preferably 20 µm or less.

[0146] In the following, a second embodiment of the method of the present invention is described with reference to Fig. 8 and Fig. 9 described.

[0147] The method of the second embodiment differs from the method of the first embodiment only in that a protective cover 30 (see Fig. 8 and Fig. 9) is applied to the first surface 4 of the substrate 2 before the pulsed laser beam LB is applied to the substrate 2.

[0148] The pulsed laser beam LB is applied to the substrate 2 such that the alignment marks 16 and the modified areas 18 are formed in essentially the same way as in the method of the first embodiment (see Fig. 8) However, the pulsed laser beam LB is applied through the protective cover 30. The protective cover 30 can be made of a material that is transparent to the pulsed laser beam LB, so that the pulsed laser beam LB is transmitted through the protective cover 30. Alternatively, the pulsed laser beam LB can cut through the protective cover 30 so that it reaches the first substrate surface 4.

[0149] The protective cover 30 is attached to the first surface 4 in such a way that it covers the components 10 formed in the component area 8. Thus, the protective cover 30 reliably protects the components 10 from contamination, for example by dirt particles, dust particles or the like, and from damage.

[0150] The protective cover 30 can have the features, properties, and characteristics described in more detail above. In particular, the protective cover 30 can include or consist of a protective film and / or a damping layer and / or a base layer, as described above.

[0151] The protective cover 30 can be provided with an adhesive layer (not shown) for attaching the protective cover 30 to the first surface 4 of the substrate 2. The adhesive layer can be arranged only in a circumferential region of the front surface of the protective cover 30. In this case, the front surface of the protective cover 30 and the first surface 4 are in direct contact with each other in a central region of the front surface of the protective cover 30. Thus, the risk of possible contamination or damage to the first surface 4, in particular to the components 10, for example due to the adhesive force of the adhesive layer or adhesive residues on the substrate 2, can be significantly reduced or even eliminated. Alternatively, the protective cover 30 can be applied to the first surface 4 in such a way that the entire front surface of the protective cover 30 is in direct contact with the first surface 4.In this case, no material, in particular no adhesive, is present between the front surface of the protective cover 30 and the first surface 4. Therefore, the risk of possible contamination or damage to the first surface 4 can be reliably eliminated.

[0152] A modification of the second embodiment of the method of the present invention is described in Fig. 9 shown. In this modification, the second embodiment is modified by enclosing a circumferential section of the protective cover 30 with an annular frame 32 (see Fig. 9) is ensured that an inner opening of the annular frame 32 is closed by the protective cover 30. In the modification of the second embodiment, the pulsed laser beam LB is also applied to the substrate 2 in such a way that the alignment marks 16 and the modified areas 18 are formed in essentially the same manner as in the method of the first embodiment (see Fig. 9).

[0153] By providing the ring-shaped frame 32, the handling of the substrate 2 in the substrate processing steps can be further facilitated and made even more efficient. In particular, this makes the step of attaching the substrate 2 to the cover 22 (see Fig. 4) be eliminated before cutting substrate 2.

[0154] In the second embodiment and its modification, the subsequent steps of cutting and dividing the substrate 2 along the dividing lines 12 are carried out in essentially the same way as in the first embodiment (see Fig. 5, Fig. 6 and Fig. 7) In particular, in the modification of the second embodiment, the protective cover 30 is radially expanded, for example by using an expansion drum or the like. In this way, a radial external force is applied to the substrate 2 such that the substrate 2 is split along the dividing lines 12 into the individual dies 28 (see Figure 1). Fig. 7) is divided.

[0155] After the substrate 2 has been completely divided in this manner, the individual dies 28 can be picked up, for example by using a pickup device (not shown).

[0156] A third embodiment of the method of the present invention is described below with reference to Fig. 10 and Fig. 11 described.

[0157] The method of the third embodiment differs from the method of the first embodiment in that the alignment marks 16 are formed in an area of ​​the second surface 6 where the back side layer 14 is not present (see Fig. 10 and Fig. 11).

[0158] As in Fig. As shown in Figure 10, the back side layer 14 covers only a portion of the second surface 6 of the substrate 2. In particular, the back side layer 14 is provided only in a central section of the second surface 6. Thus, the back side layer 14 is not present in a circumferential section 34 of the second surface 6 that surrounds the central section of the second surface 6. The circumferential section 34 can have a shape that is at least substantially ring-shaped. The circumferential section 34 can have a width, for example, a ring width, in the range of 0.1 mm to 3 mm. In the present embodiment, the back side layer 14 is present substantially only in a region of the second surface 6 that corresponds to the component area 8 formed on the first surface 4.

[0159] In the method of the third embodiment, all alignment marks 16 are formed in the circumferential section 34 of the second surface 6, in which the back side layer 14 is not present (see Fig. 10) In particular, the alignment marks 16 are formed by placing the focal point of the pulsed laser beam LB at a position that is located at least substantially on the second surface 6 in its circumferential section 34 (see Fig. 10) By arranging the focal point at least substantially on the second surface 6, a significant portion of the pulsed laser beam LB is absorbed on this surface, thereby forming alignment marks 16 in the circumferential section 34, which are clearly visible from the side of the second surface 6.

[0160] By using these alignment marks 16, the cutting blade 26 can be reliably and accurately aligned relative to the dividing lines 12 for the subsequent step of cutting the substrate 2 along the dividing lines 12.

[0161] In the method of the third embodiment, the modified areas 18 are formed in the substrate 2 in the same way as in the method of the first embodiment. The pulsed laser beam LB applied to the substrate 2 to form the multiple modified areas 18 can be the same as the pulsed laser beam LB applied to the substrate 2 to form the multiple alignment marks 16. Alternatively, two different laser beams can be used for these purposes.

[0162] A modification of the third embodiment of the method of the present invention is described in Fig. 11 shown. In this modification, the third embodiment is modified by attaching the second surface 6 of the substrate 2 to a cover 36 (see Fig. 11). A circumferential section of the cover 36 is thus held by an annular frame 38 (see Fig. 11) that an inner opening of the ring-shaped frame 38 is closed by the cover 36.

[0163] The cover 36 can be a standard dividing belt or a protective cover, such as the protective cover 30 described above.

[0164] By attaching the second surface 6 of the substrate 2 to the cover 36 held by the ring-shaped frame 38, the handling of the substrate 2 in the substrate processing steps can be further facilitated and made even more efficient.

[0165] In the third embodiment and its modification, the subsequent steps of cutting and dividing the substrate 2 along the dividing lines 12 are carried out in essentially the same way as in the first embodiment (see Fig. 5, Fig. 6 and Fig. 7).

[0166] After the substrate 2 has been completely divided in this manner, the individual dies 28 can be picked up, for example by using a pickup device (not shown).

[0167] In the following, a fourth embodiment of the method of the present disclosure is described with reference to Fig. Described in sections 12 to 17.

[0168] The method of the fourth embodiment differs from the method of the first embodiment essentially in that the alignment marks 16 are formed in a protective cover.

[0169] In the fourth embodiment, a protective cover is applied to the first surface 4 of the substrate 2 before the pulsed laser beam LB is applied to the substrate 2. In the present embodiment, the protective cover is the protective cover 30, and it can have the features, properties, and characteristics described above. In particular, the protective cover 30 can be applied to the first surface 4 with or without an adhesive layer (not shown), as described in more detail above.

[0170] The protective cover 30 is attached to the first surface 4 in such a way that it covers the components 10 formed in the component area 8. The protective cover 30 protects the first surface 4, in particular the components 10, from contamination and damage.

[0171] As in Fig. As shown in Figure 12, a section 40 of the protective cover 30 extends laterally beyond the first surface 4. The section 40 of the protective cover 30 surrounds the first surface 4. The section 40 can have a substantially ring-shaped form. In other embodiments, for example, in the case of a substrate with a rectangular or square shape, the section 40 can have at least a substantially open rectangular shape or an open square shape, that is, a rectangular or square shape with an opening in its center.

[0172] After the protective cover 30 is attached to the first surface 4, modified areas 18 are formed in the substrate 2 and alignment marks 16 are formed in the protective cover 30, as shown in Fig. Figure 13 illustrates this. The order of these two steps is not particularly restricted. For example, the modified areas 18 can be formed before the alignment marks 16. Alternatively, the alignment marks 16 can be formed before the modified areas 18.

[0173] The pulsed laser beam LB is applied to the substrate 2 in such a way that the modified areas 18 are formed in the substrate 2 in essentially the same way as in the method of the second embodiment (see Fig. 8 and Fig. 13) In particular, the pulsed laser beam LB is applied through the protective cover 30. The protective cover 30 can be made of a material that is transparent to the pulsed laser beam LB, so that the pulsed laser beam LB is transmitted through the protective cover 30. Alternatively, the pulsed laser beam LB can cut through the protective cover 30 so that it reaches the first substrate surface 4.

[0174] The pulsed laser beam LB is applied to the protective cover 30 such that the alignment marks 16 are formed in the protective cover 30. Specifically, the alignment marks 16 are formed in the protective cover 30 by positioning the focal point of the pulsed laser beam LB at locations in the protective cover 30 where the alignment marks 16 are to be formed. All alignment marks 16 are formed in the section 40 of the protective cover 30 that extends laterally beyond the first surface 4 (see Figure 1). Fig. 13). In this way, the cutting blade 26 can be aligned with particularly high alignment accuracy relative to the separation lines 12, thus enabling the substrate cutting process (see Fig. 14) to be carried out with a particularly high degree of precision.

[0175] In the present embodiment, the pulsed laser beam LB applied to form the modified areas 18 on the substrate 2 can be the same as the pulsed laser beam LB applied to form the alignment marks 16 on the protective cover 30. Alternatively, two different laser beams can be used for these purposes.

[0176] After all alignment marks 16 and modified areas 18 have been formed, the substrate 2 is attached to another cover 42 (see Fig. 14) In particular, the first surface 4 of the substrate 2, which has the protective cover 30 provided thereon, is attached to the cover 42. The cover 42 can be a conventional dividing belt. The cover 42 is held at a circumferential section thereof by an annular frame 44 such that an inner opening of the annular frame 44 is closed by the cover 42, as shown in Fig. Figure 14 shows that this further simplifies the handling of substrate 2 in the substrate processing steps.

[0177] After the substrate 2 is attached to the cover 42, the substrate 2 is cut in essentially the same way as in the method of the first embodiment by using the cutting blade 26 from the side of the second surface 6 along the dividing lines 12 (see Fig. 14). In particular, the substrate 2 is cut through the back layer 14 along the separation lines 12.

[0178] The alignment marks 16 formed in section 40 of the protective cover 30, which are clearly visible from the side of the second surface 6 (see Fig. 14) are used to align the cutting blade 26 relative to the parting lines 12 to be cut. Therefore, the cutting blade 26 can be aligned with increased accuracy relative to the parting lines 12, enabling the substrate cutting process to be carried out with a high degree of precision. Consequently, the width of the parting lines 12 can be reduced, allowing for the inclusion of an increased number of components 10 on the first surface 4. In this way, manufacturing efficiency is significantly increased and the waste of substrate material is avoided.

[0179] After the substrate 2 has been cut along all the dividing lines 12, the cover 42 is radially expanded, for example by using an expanding drum or the like. In this way, a radial external force is applied to the substrate 2 such that the substrate 2 is divided into the individual dies 28 along the dividing lines 12 in essentially the same way as in the method of the first embodiment (see Fig. 7).

[0180] After the substrate 2 has been completely divided in this way, the individual dies 28 can be picked up, for example by using a pickup device (not shown).

[0181] A modification of the fourth embodiment of the method of the present disclosure is in Fig. Figures 15 to 17 show that in this modification the fourth embodiment is modified by using a protective cover 30 which extends laterally further beyond the first surface 4 than the protective cover 30 of the fourth embodiment, and by attaching an outermost laterally bound section of the protective cover 30 to an annular frame 46 (see Figures 15 to 17). Fig. 15) The protective cover 30 is attached to the ring-shaped frame 46 in such a way that an inner opening of the ring-shaped frame 46 is closed by the protective cover 30.

[0182] By providing the ring-shaped frame 46 in this manner, the handling of the substrate 2 in the substrate processing steps can be further facilitated and made even more efficient. In particular, the step of attaching the substrate 2 to the cover 42 (see Figure 4) can be made easier. Fig. 14) be eliminated before cutting substrate 2.

[0183] After the protective cover 30 is attached to the first surface 4, modified areas 18 are formed in the substrate 2 and alignment marks 16 are formed in the protective cover 30 in essentially the same way as in the method of the fourth embodiment (see Fig. 13 and Fig. 16).

[0184] After all alignment marks 16 and modified areas 18 have been formed, the substrate 2 is cut in essentially the same way as in the method of the fourth embodiment by using the cutting blade 26 from the side of the second surface 6 along the dividing lines 12 (see Fig. 14 and Fig. 17).

[0185] Subsequently, after the substrate 2 has been cut along all separation lines 12, the protective cover 30 is radially expanded, for example by using an expanding drum or the like. In this way, a radial external force is applied to the substrate 2 such that the substrate 2 is divided along the separation lines 12 into the individual dies 28 (see Fig. 7) In the modified method of the fourth embodiment, only a single cover, namely the protective cover 30, is attached to the first surface 4 of the substrate 2. Therefore, the process of dividing the substrate 2 can be carried out in a particularly efficient and reliable manner by radially widening the protective cover 30.

[0186] After the substrate 2 has been completely divided in this manner, the individual dies 28 can be picked up, for example by using a pickup device (not shown).

[0187] In the following, a fifth embodiment of the method of the present disclosure is described with reference to Fig. 18 to 20 described.

[0188] The method of the fifth embodiment differs from the method of the modification of the fourth embodiment with regard to the construction of the protective cover 30.

[0189] In particular, the protective cover 30 in the method of the fifth embodiment comprises a base layer 48 and a damping layer 50 (see Fig. 18) The damping layer 50 is applied to the first surface 4. Furthermore, a protective film (not shown) is provided such that it is positioned between the first surface 4 and the damping layer 50, as described in more detail above. The protective film is also positioned between the side walls of the substrate 2 and the damping layer 50. Providing the protective film reliably prevents the substrate 2 from being contaminated by the material of the damping layer 50. The protective film can be applied to the first surface 4 with or without an adhesive layer, as described in more detail above.

[0190] Essentially, the entire substrate 2 is embedded in the damping layer 50. However, a rear surface 52 of the back side layer 14 is exposed, i.e., not covered by the damping layer 50 (see Fig. 18). The damping layer 50 can have a thickness that is essentially the same as the thickness of the substrate 2, for example 100 to 150 µm.

[0191] Section 40 of the protective cover 30, which extends laterally beyond the first surface 4 and is formed to a substantial extent by the damping layer 50, extends from the first surface 4 substantially along the entire thickness of the substrate 2 towards the second surface 6 (see Fig. 18).

[0192] The protective cover 30, which comprises the base layer 48, the damping layer 50, and the protective film, serves as a particularly reliable support for holding the substrate 2 during the substrate cutting and dividing processes. Unwanted displacement of the substrate 2 or the resulting die 28 (see Fig. 7) can be reliably avoided.

[0193] A front surface of the base layer 48 is in contact with a rear surface of the damping layer 50. A rear surface of the base layer 48, opposite its front surface, can be substantially parallel to the second surface 6 of the substrate. Thus, when the substrate 2 is cut along the parting lines 12 from the side of the second surface 6 using the cutting blade 26, suitable counter-pressure can be applied to the rear surface of the base layer 48, for example by positioning this rear surface on a clamping table (not shown).

[0194] The material of the base layer is not particularly restricted. For example, the base layer can consist of a polymer material, such as polyvinyl chloride (PVC), ethylene vinyl acetate (EVA), or a polyolefin.

[0195] The material of the damping layer is not particularly restricted. For example, the damping layer can be made of a resin, an adhesive, a gel, or the like.

[0196] The material of the protective film is not particularly restricted. For example, the protective film can be made of a plastic material, such as a polymer, for example, a polyolefin. In particular, the protective film can be made of polyethylene (PE), polypropylene (PP), or polybutylene (PB).

[0197] The base layer 48, the damping layer 50 and the protective film consist of materials that are transparent to the pulsed laser beam LB, so that the pulsed laser beam LB is transmitted through the base layer 48, the damping layer 50 and the protective film.

[0198] After the protective cover 30 is attached to the first surface 4, modified areas 18 are formed in the substrate 2 and alignment marks 16 are formed in the protective cover 30, as shown in Fig. Figure 19 illustrates this. The order of these two steps is not particularly restricted. For example, the modified areas 18 can be formed before the alignment marks 16. Alternatively, the alignment marks 16 can be formed before the modified areas 18.

[0199] The pulsed laser beam LB is applied to the substrate 2 in such a way that the modified areas 18 are formed in the substrate 2 in essentially the same way as in the method of the second embodiment (see Fig. 8 and Fig. 19). In particular, the pulsed laser beam LB is applied through the protective cover 30, which is transparent to the pulsed laser beam LB.

[0200] The pulsed laser beam LB is applied to the protective cover 30 such that the alignment marks 16 are formed in the protective cover 30. All alignment marks 16 are formed in the section 40 of the protective cover 30 that extends laterally beyond the first surface 4. In particular, all alignment marks 16 are formed at a position in the damping layer 50 that is located at least substantially on the second surface 6 of the substrate 2 (see Fig. 19). In this way, the alignment accuracy with which the cutting blade 26 can be aligned relative to the dividing lines 12 can be determined (see Fig. 20), will be increased even further.

[0201] In the present embodiment, the pulsed laser beam LB applied to form the modified areas 18 on the substrate 2 can be the same as the pulsed laser beam LB applied to form the alignment marks 16 on the protective cover 30. Alternatively, two different laser beams can be used for these purposes.

[0202] After all alignment marks 16 and modified areas 18 have been formed, the substrate 2 is cut in essentially the same way as in the method of the first embodiment by using the cutting blade 26 from the side of the second surface 6 along the parting lines 12 (see Fig. 20). In particular, the substrate 2 is cut through the back layer 14 along the separation lines 12.

[0203] The alignment marks 16 formed in the damping layer 50 of the protective cover 30, which are particularly clearly visible from the side of the second surface 6 (see Fig. 20) are used to align the cutting blade 26 relative to the separation lines 12 to be cut. Therefore, the cutting blade 26 can be aligned with even greater accuracy relative to the separation lines 12, thus enabling the substrate cutting process to be carried out with a particularly high degree of precision.

[0204] After the substrate 2 has been cut along all separation lines 12, the protective cover 30 is radially expanded, for example by using an expanding drum or the like. In this way, a radial external force is applied to the substrate 2 such that the substrate 2 is divided into the individual dies 28 along the separation lines 12 in essentially the same way as in the method of the first embodiment (see Fig. 7).

[0205] After the substrate 2 has been completely divided in this manner, the individual dies 28 can be picked up, for example by using a pickup device (not shown).

[0206] The following numbered paragraphs are also part of the disclosure: 1. Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), the method comprising: Attaching a protective cover (30) to the first surface (4), Applying a laser beam (LB) to the protective cover (30) so that several alignment marks (16) are formed in the protective cover (30), and Removal of substrate material along the at least one separation line (12) from the side of the second surface (6) by using a substrate material removal agent (26), wherein the alignment marks (16) are used to align the substrate material removal agent (26) relative to the at least one dividing line (12). 2. Procedure according to 1, in which a section (40) of the protective cover (30) extends laterally beyond the first surface (4), and at least one of the alignment marks (16) is formed in the section (40) of the protective cover (30) which extends laterally beyond the first surface (4). 3. Procedure according to 2, in which the section (40) of the protective cover (30) which extends laterally beyond the first surface (4) and extends along a thickness direction of the substrate (2) from the first surface (4) to the second surface (6), and at least one of the alignment marks (16) in the section (40) of the protective cover (30) which extends laterally beyond the first surface (4) is formed in a position that is closer to the second surface (6) than to the first surface (4). 4. Method according to one of 1 to 3, wherein a back side layer (14), in particular a metal layer, is formed on the second surface (6). 5. Method according to one of 1 to 4, wherein the protective cover (30) consists of a material that is transparent to the laser beam (LB). 6. Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), wherein a back side layer (14) is formed on the second surface (6) and the method comprises: Applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) in a state in which a focal point of the laser beam (LB) is located at a position within the substrate (2) that is closer to the second surface (6) than to the first surface (4), such that several alignment marks (16) are formed in the backside layer (14) and / or in a region of the second surface (6) where the backside layer (14) is not present, and Removal of substrate material along the at least one dividing line (12) from the side of the second surface (6) from by using a substrate material removal agent (26), wherein the alignment marks (16) are used to align the substrate material removal agent (26) relative to the at least one dividing line (12). 7. Method according to 6, wherein the back side layer (14) is a metal layer. 8. Method according to 6 or 7, further comprising attaching a protective cover (30) to the first surface (4), wherein the protective cover (30) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) through the protective cover (30). 9. Method according to one of 1 to 8, further comprising applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) consists of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) at least at several positions along the at least one dividing line (12) such that several modified areas (18) are formed in the substrate (2). 10. Method according to one of 1 to 9, wherein the substrate material is mechanically removed along the at least one separation line (12), in particular by mechanically cutting the substrate (2) along the at least one separation line (12). 11. Method according to one of 1 to 9, wherein the substrate material is removed along the at least one separation line (12) by laser cutting, in particular by laser ablation. 12. Method according to one of 1 to 11, wherein the substrate material is removed only along a part of the thickness of the substrate (2) in the direction from the second surface (6) to the first surface (4). 13. Method according to one of 1 to 12, further comprising applying an external force to the substrate (2) after substrate material has been removed along the at least one dividing line (12), so that the substrate (2) is divided along the at least one dividing line (12).

Claims

[1] Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), wherein a back side layer (14) is formed on the second surface (6) and the method comprises: Applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) in a state in which a focal point of the laser beam (LB) is located at a position within the substrate (2) that is closer to the second surface (6) than to the first surface (4), such that several alignment marks (16) are formed in the backside layer (14) and / or in a region of the second surface (6) where the backside layer (14) is not present, and Removal of substrate material along the at least one separation line (12) from the side of the second surface (6) by using a substrate material removal agent (26), wherein the alignment marks (16) are used to align the substrate material removal agent (26) relative to the at least one dividing line (12). [2] Method according to claim 1, wherein the back side layer (14) is a metal layer. [3] Method according to claim 1 or 2, further comprising attaching a protective cover (30) to the first surface (4), wherein the protective cover (30) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) through the protective cover (30). [4] Method according to one of the preceding claims, further comprising applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) consists of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) at least at several positions along the at least one dividing line (12) such that several modified areas (18) are formed in the substrate (2). [5] Method according to any of the preceding claims, wherein the substrate material is mechanically removed along the at least one separation line (12), in particular by mechanically cutting the substrate (2) along the at least one separation line (12). [6] Method according to any one of claims 1 to 4, wherein the substrate material is removed along the at least one separation line (12) by laser cutting, in particular by laser ablation. [7] Method according to one of the preceding claims, wherein the substrate material is removed only along a part of the thickness of the substrate (2) in the direction from the second surface (6) to the first surface (4). [8] Method according to any of the preceding claims, further comprising applying an external force to the substrate (2) after substrate material has been removed along the at least one dividing line (12), so that the substrate (2) is divided along the at least one dividing line (12).

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