Method of splitting a semiconductor substrate and substrate splitting apparatus

Abstract

A method of splitting a semiconductor substrate includes forming a release layer (115) in a semiconductor substrate (110), wherein the semiconductor substrate (110) includes a first substrate portion (114) between a first surface (111) and the release layer (115) and a second substrate portion (116) between the release layer (115) and a second surface (112) opposite the first surface (111). An auxiliary layer (120) is formed on the first surface (111), wherein the auxiliary layer (120) and the semiconductor substrate (110) have different coefficients of thermal expansion. A main cooling plate (210) is brought into contact with a solid substrate composite (100) that includes the semiconductor substrate (110) and the auxiliary layer (120) in a cooling period. The main cooling plate (210) is cooled in the cooling period, wherein the auxiliary layer (120) is cooled. Mechanical vibrations are applied directly to the main cooling plate (210) in the cooling period, wherein the first substrate portion (114) is cleaved from the second substrate portion (116).

Description

[0001] Infineon Technologies AG 2024P07160 WO

[0002] 1

[0003] METHOD OF SPLITTING A SEMICONDUCTOR SUBSTRATE AND SUBSTRATE SPLITTING APPARATUS

[0004] TECHNICAL FIELD

[0005] The present disclosure relates to methods of splitting a semiconductor substrate and to substrate splitting apparatuses.

[0006] BACKGROUND

[0007] Thin crystalline semiconductor substrates, such as semiconductor wafers, can be cleaved from a crystalline boule by sawing or by cleaving along prepared release planes, wherein the release planes are formed by locally modifying the boule material by laser irradiation, ion implantation or other methods. Mechanical forces then cleave the crystalline boule along the release plane. In some methods, an auxiliary layer made of a material with a coefficient of thermal expansion that differs significantly from the coefficient of thermal expansion of the crystalline boule is firmly bonded to the crystalline boule. A temperature treatment of the substrate composite, including the crystalline boule and the auxiliary layer, generates thermomechanical stresses and the crystalline boule splits along the release layer. There is a constant need to improve the yield of thin substrates obtained from crystalline boules by splitting processes.

[0008] SUMMARY

[0009] An example of the present disclosure relates to a method of splitting a semiconductor substrate. The method includes forming a release layer in a semiconductor substrate that includes a first substrate portion between a first surface and the release layer and a second substrate portion between the release layer and a second surface opposite the first surface. An auxiliary layer is formed on the first surface, wherein the auxiliary layer and the semiconductor substrate have different coefficients of thermal expansion. A main cooling plate is brought into contact with a solid substrate composite including the semiconductor substrate and the auxiliary layer in a cooling period. The main cooling plate is cooled in the cooling period, wherein the auxiliary layer is cooled. Mechanical vibrations are directly applied to the Infineon Technologies AG 2024P07160 WO

[0010] 2 main cooling plate in the cooling period, wherein the first substrate portion is cleaved from the second substrate portion.

[0011] If the semiconductor substrate is comparatively thin, the semiconductor substrate sometimes cannot withstand the forces required to trigger the splitting process by cooling the solid substrate composite, with the result that the semiconductor substrate breaks outside the release layer. By applying the mechanical vibrations, the splitting process along the release layer can be triggered at significantly lower thermomechanical stresses. The probability of the semiconductor substrate breaking outside the release layer can be reduced. The yield of the splitting process can be improved.

[0012] Another example of the present disclosure relates to another method of splitting a semiconductor substrate. The method includes forming a release layer in a semiconductor substrate, wherein the semiconductor substrate includes a first substrate portion between a first surface and the release layer and a second substrate portion between the release layer and a second surface opposite the first surface. An auxiliary layer is formed on the first surface, wherein the auxiliary layer and the semiconductor substrate have different coefficients of thermal expansion. A main cooling plate is brought into contact with a solid substrate composite including the semiconductor substrate and the auxiliary layer in a cooling period. A vibration plate is brought into contact with the solid substrate composite at a side opposite the main cooling plate. The main cooling plate is cooled in the cooling period, wherein the auxiliary layer is cooled. Mechanical vibrations are applied to the solid substrate composite by using the vibration plate in and / or after the cooling period, wherein the first substrate portion is cleaved from the second substrate portion.

[0013] Another example of the present disclosure relates to a substrate splitting apparatus. The substrate splitting apparatus includes a main cooling plate and a vibration excitation source. The main cooling plate includes a main cooling surface and is configured to bring the main cooling surface into direct contact with a solid substrate composite in a cooling period. The vibration excitation source is configured to excite vibrations of the main cooling plate along at least one spatial axis in the cooling period. Infineon Technologies AG 2024P07160 WO

[0014] 3

[0015] Another example of the present disclosure relates to another substrate splitting apparatus. The substrate splitting apparatus includes a main cooling plate and a vibration plate. The main cooling plate includes a main cooling surface and is configured to bring the main cooling surface into direct contact with a solid substrate composite for a cooling period. The vibration plate includes an auxiliary surface opposite the main cooling surface of the main cooling plate. The main cooling plate and the vibration plate are configured to clamp the solid substrate composite between the main cooling surface and the auxiliary surface in the cooling period. The vibration plate is further configured to excite vibrations of the solid substrate composite along at least one spatial axis in and / or after the cooling period.

[0016] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar or identical elements. The elements of the drawings are not necessarily to scale relative to each other. The features of the various illustrated examples can be combined unless they exclude each other.

[0019] Fig. 1A to 1 D illustrate a method of splitting a semiconductor substrate using a main cooling plate in support configuration in accordance with an embodiment.

[0020] Fig. 2A to 2B illustrate a cooling phase of a method of splitting a semiconductor substrate using a main cooling plate in suspension configuration in accordance with an embodiment.

[0021] Fig. 3 illustrates a main cooling plate with piezo actuators attached in suspension configuration in combination with a counter plate in support configuration in a cooling period of a solid substrate composite in accordance with an embodiment. Infineon Technologies AG 2024P07160 WO

[0022] 4

[0023] Fig. 4A to 4B illustrate phases of a method of splitting a semiconductor substrate using a main cooling plate in suspension configuration and an auxiliary cooling plate in support configuration in accordance with an embodiment.

[0024] Fig. 5 illustrates a cooling phase of a method of splitting a semiconductor substrate using a vibration-free main cooling plate in suspension configuration and a vibration plate in support configuration in accordance with another embodiment.

[0025] Fig. 6 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a main cooling plate configured to vibrate and a substrate holder in accordance with an embodiment related to a main cooling plate in suspension configuration.

[0026] Fig. 7 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a main cooling plate configured to vibrate and a substrate holder in accordance with an embodiment related to a main cooling plate in support configuration.

[0027] Fig. 8 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a counter plate and a main cooling plate with piezo actuators in accordance with an embodiment related to a main cooling plate in suspension configuration.

[0028] Fig. 9 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a main cooling plate with piezo actuators integrated in suspension units in accordance with an embodiment.

[0029] Fig. 10 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a main cooling plate configured to vibrate and a non-vibrating auxiliary cooling plate in accordance with an embodiment.

[0030] Fig. 11 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a main cooling plate configured to vibrate and an auxiliary cooling plate configured to vibrate in accordance with an embodiment. Infineon Technologies AG 2024P07160 WO

[0031] 5

[0032] Fig. 12 is a schematic vertical cross-sectional view of a substrate splitting apparatus including a vibration-free main cooling plate in suspension configuration and a vibration plate in support configuration in accordance with another embodiment.

[0033] DETAILED DESCRIPTION

[0034] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof and in which are shown by way of illustrations specific examples of methods and apparatuses for separating semiconductor substrates. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. For example, features illustrated or described for one example can be used in conjunction with other examples to yield yet a further example. It is intended that the present disclosure includes such modifications and variations. The examples are described using specific language, which should not be construed as limiting the scope of the appending claims. The drawings are not scaled and are for illustrative purposes only. Corresponding elements are designated by the same reference signs in the different drawings if not stated otherwise.

[0035] The terms "having", "containing", "including", "including" and the like are open, and the terms indicate the presence of stated structures, elements or features but do not preclude the presence of additional elements or features. The articles "a", "an" and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0036] Ranges given for physical dimensions include the boundary values. For example, a range for a parameter y from a to b reads as a < y < b. The same holds for ranges with one boundary value like “at most” and “at least”.

[0037] The terms "on" and “over” are not to be construed as meaning only "directly on" and “directly over”. Rather, if one element is positioned "on" or “over” another element (e.g., a layer is "on" or “over” another layer or "on" or “over” a substrate), a further component (e.g., a further layer) may be positioned between the two elements (e.g., a further layer may be positioned between a layer and a substrate if the layer is "on" or “over” said substrate). Infineon Technologies AG 2024P07160 WO

[0038] 6

[0039] An example of the present disclosure relates to a method of splitting a semiconductor substrate. The method may include forming a release layer in a semiconductor substrate, wherein the semiconductor substrate may include a first substrate portion between a first surface and the release layer and may include a second substrate portion between the release layer and a second surface opposite the first surface. An auxiliary layer may be formed on the first surface. The auxiliary layer and the semiconductor substrate may have different coefficients of thermal expansion. A main cooling plate may be brought into contact with a solid substrate composite that includes the semiconductor substrate and the auxiliary layer in a cooling period. The main cooling plate may be cooled in the cooling period, wherein the auxiliary layer is cooled. Mechanical vibrations may be directly applied to the main cooling plate in and / or after the cooling period, wherein the first substrate portion may be cleaved from the second substrate portion.

[0040] The semiconductor substrate may be e.g. a wafer or a boule. . The shape of the semiconductor substrate may be a cylinder with an approximately planar first surface at one end of the cylinder and an approximately planar second surface at the other end. The first surface and the second surface may be parallel or at least approximately parallel to each other. The cylinder may be a right cylinder, e.g., a right circular cylinder with a circular base. In other examples, the base of the cylinder may be a circle with a notch or flat. The semiconductor substrate may be a so- called semiconductor puck, which is sometimes also referred to as a semiconductor boule or ingot. The semiconductor substrate may be a polycrystalline or single-crystalline semiconductor substrate (e.g. a single-crystalline puck).

[0041] The semiconductor may be an elementary semiconductor like silicon Si or germanium Ge or a compound semiconductor, e.g. a group IV compound semiconductor such as silicon carbide SiC, or a group lll / V compound semiconductor such as gallium arsenide GaAs orgallium nitride GaN. In an example, the semiconductor substrate is a SiC wafer or a SiC puck with polished surfaces.

[0042] The release layer can be formed by laser irradiation through the first surface and / or the second surface, wherein the laser radiation is focused to a predefined distance from the entrance surface. The focused laser radiation locally heats the crystal structure and locally modifies the crystalline lattice. In modified regions, the crystal lattice is severely damaged, e.g. amorphized. Infineon Technologies AG 2024P07160 WO

[0043] 7

[0044] In the modified regions of a compound semiconductor, the compound may be separated into its components. In addition, the heating may generate subcritical cracks in the semiconductor substrate, wherein the subcritical cracks originate at or near the modified regions and propagate along main crystal planes. Alternatively, the release layer may be formed by implanting ions through the first surface and / or the second surface, or by other forms of particle and / or electromagnetic radiation locally modifying the crystalline lattice of the semiconductor substrate.

[0045] The coefficient of thermal extension (CTE) of the auxiliary layer can deviate considerably from the CTE of the semiconductor substrate. For example, the CTE of the auxiliary layer can be at least ten times, e.g. at least 30 times or at least 50 times greater than the CTE of the semiconductor substrate. In addition to the CTE difference, a linear progression of the CTE in the auxiliary layer over a wide temperature range can be advantageous. The auxiliary layer can have a comparatively high thermal conductivity.

[0046] Forming the auxiliary layer on the first surface of the semiconductor substrate may include a bonding process to allow for a firm bond to form that is resilient against the following cooling process. For example, before applying the auxiliary layer, an application surface of the auxiliary layer and / or the first surface of the semiconductor substrate may undergo chemical and / or physical surface treatment (for example, with a plasma). The surface treatment may remove impurities, may planarize the surface, and / or may activate / deactivate surface bonds.

[0047] In addition to the semiconductor substrate and the auxiliary layer, the solid substrate composite may include one or more additional layers, films, and / or foils. For example, a transport foil may be attached to the side of the auxiliary layer opposite the semiconductor substrate. Alternatively or in addition, an auxiliary foil may be attached to the second surface of the semiconductor substrate. Alternatively or in addition, a separation foil may be provided between the semiconductor substrate and the auxiliary layer. Each of the additional layers, films, and / or foils may be homogenous or may include two or more sub-layers of different composition. Each of the additional layers and / or films may be thinner than the auxiliary layer. The auxiliary layer may have a thermal conductivity of at least 0.1 W / (m*K). Infineon Technologies AG 2024P07160 WO

[0048] 8

[0049] The main cooling plate may include two parallel plate portions and a coolant duct formed along an interface between two plate portions. Each of the plate portions may include a main part formed from an elementary metal, e.g. copper Cu or aluminum Al, a metal compound or a metal alloy. The main cooling plate can be in a support configuration, where the cooling surface is oriented against the direction of gravity (upwards), or in a suspension configuration, where the cooling surface is oriented in the direction of gravity (downwards).

[0050] Bringing the main cooling plate into direct contact with the solid substrate composite may include placing the solid substrate composite on the cooling surface in case the main cooling plate has a support configuration or lowering the main cooling plate in direction of a solid substrate composite placed below the cooling surface until the cooling surface reaches the solid substrate composite and is in solid-state contact with the solid substrate composite.

[0051] The period, for which the main cooling plate is in direct solid-state contact with the solid substrate composite defines the cooling period, irrespective of a temperature difference between the main cooling plate and the solid substrate composite.

[0052] Cooling the main cooling plate may include feeding a coolant, e.g. liquid nitrogen N2, into the coolant duct in response to a control signal received from a control unit. The main cooling plate cools the solid substrate composite including the auxiliary layer in the cooling period. The coolant flow may start before the cooling period, i.e., before a direct solid-state contact is established between the main cooling plate and the solid substate composite, simultaneously with the establishment of the solid-state contact, or after establishment of the solid-state contact. The coolant flow can end before the end of the cooling period, i.e., before the direct solid-state contact between the main cooling plate and the solid substate composite is released, simultaneously with the release of the solid-state contact, or after the solid-state contact is released. During the cooling period, the coolant flow may be constant or may vary with time.

[0053] The comparatively high difference in CTE in combination with the strong bond between the semiconductor substrate and the auxiliary layer effects a high thermomechanical stress in the auxiliary layer and the semiconductor substrate. In the semiconductor substrate, the subcritical cracks can propagate further along the main crystal planes. Depending on the crystal lattice of Infineon Technologies AG 2024P07160 WO

[0054] 9 the semiconductor substrate and the orientation of main crystal planes with respect to the first surface and the second surface, the crystal may crack between lattice defects in different crystal planes. Regardless of the lattice type and lattice orientation, a continuous crack surface may develop, which finally separates the semiconductor substrate completely into the first portion and the second portion in most cases.

[0055] If a total thickness of the semiconductor substrate is less than a critical thickness, then the high mechanical forces effective between the auxiliary layer and the semiconductor substrate result in a significant bending of the solid substrate composite. Then the mechanical strength of the semiconductor substrate may be insufficient to survive the cooling cycle and the semiconductor substrate may break outside the release layer before a continuous crack surface completely separates the semiconductor substrate into the first portion and the second portion. In addition, a propagation of the continuous crack surface may come to a standstill before the first portion is completely separated from the second portion. For example, the continuous crack surface may leave out a central part of the release layer. For a singlecrystalline SiC puck or SiC wafer, the critical thickness may be 3 mm or less, e.g. 2 mm or 1.5 mm.

[0056] Applying the mechanical vibrations to the main cooling plate may begin with the begin of the cooling period or later, e.g. when the main cooling plate or the auxiliary layer reaches a predetermined temperature. The mechanical vibrations may include a sequence of pulses and / or oscillations. The main cooling plate may vibrate along a vertical axis orthogonal to the cooling surface and / or in a horizontal plane parallel to the cooling surface and / or around a vertical rotational axis through a vertical axis of symmetry of the main cooling plate. The amplitude of the mechanical vibrations may be constant or vary over time. A maximum amplitude of the vibrations of the main cooling plate may be in a range from 10 nm to 100 pm. A frequency of the pulses and / or oscillations may be constant or vary over time. A maximum frequency of the vibrations of the main cooling plate may be in a range from 1 Hz to 100kHz.

[0057] By applying the mechanical vibrations, a continuous crack surface may develop across the entire cross-section of the semiconductor substrate even at higher temperatures and lower thermomechanical stresses than without vibrations. It may be possible to complete the splitting process along the release layer at significantly lower thermomechanical stresses. The Infineon Technologies AG 2024P07160 WO

[0058] 10 probability of the semiconductor substrate breaking outside the release layer may be reduced.

[0059] The yield of the splitting process may be improved.

[0060] According to an example, the auxiliary layer may include a material exhibiting a glass transition at a glass transition temperature, wherein the auxiliary layer is cooled to a temperature below the glass transition temperature.

[0061] The auxiliary layer may include or consist of any material that undergoes a glass transition, such as a polymer, another organic glass, or an inorganic glass. The glass transition may significantly change mechanical properties such as viscosity and / or elasticity of the material passing through the glass transition. The glass transition may cause the auxiliary layer to become harder and / or more brittle, so that the auxiliary layer can exert significant higher mechanical stress on the semiconductor substrate after the glass transition than before the glass transition. The CTE of the auxiliary layer may be at least 250 ppm / °C (250* 10'6K'1), for example at least 300 ppm / °C (300* 10'6K'1).

[0062] According to an example, the release layer may be formed by locally modifying composition and / or structure of the semiconductor substrate. The release layer can be formed by laser irradiation through the first surface and / or the second surface, wherein the laser radiation is focused at a predefined distance from the entrance surface. The focused laser radiation may locally heat the crystal structure and locally modify the crystalline lattice. In modified regions, the crystal lattice is severely damaged, e.g. amorphized. In the modified regions of a compound semiconductor, the compound may be separated into the components. In addition, the heating may generate subcritical cracks in the semiconductor substrate, wherein the subcritical cracks originate at or near the modified regions and propagate along main crystal planes. The subcritical cracks are sufficiently short such that the majority of the subcritical cracks do not merge with each other and no continuous split-off plane is formed across the complete crosssection of the semiconductor substrate. A maximum lateral extension of a subcritical crack may be smaller than a lateral distance between neighboring modified regions. Alternatively, the release layer may be formed by implanting ions through the first surface and / or the second surface, or by other forms of particle and / or electromagnetic radiation locally modifying the crystalline lattice of the semiconductor substrate. Infineon Technologies AG 2024P07160 WO

[0063] 11

[0064] According to an example, the main cooling plate may be brought into direct contact with the auxiliary layer or the semiconductor substrate. A solid-state contact between the main cooling plate and the auxiliary layer or the semiconductor substrate may provide high thermal conductivity between the main cooling plate and the semiconductor substrate and a short process time.

[0065] According to an example, the mechanical vibrations may be applied to a side of the main cooling plate opposite the solid substrate composite. The side of the main cooling plate opposite the solid substrate composite (cooling plate backside) is typically easily accessible for installation of additional components.

[0066] According to an example, the mechanical vibrations may be generated by one or more vibration excitation source attached to the main cooling plate. In particular, the vibration excitation source or vibration excitation sources can be installed on the cooling plate back side, which is typically easily accessible for installation of additional components.

[0067] According to an example, the mechanical vibrations may be generated after the auxiliary layer has reached the target temperature. Applying the mechanical vibrations at an early stage may induce an erratic development of the subcritical cracks. Applying the mechanical vibrations only after some thermomechanical stresses has been generated may support a more controlled initial phase of the development of a continuous crack surface.

[0068] According to an example, the method may further include bringing an auxiliary cooling plate into direct contact with a side of the solid substrate composite opposite the main cooling plate and cooling the auxiliary cooling plate.

[0069] For example, the main cooling plate is in direct solid-state contact with the semiconductor substrate or with an additional layer, film or foil on the side of the semiconductor substrate opposite the auxiliary layer, and the auxiliary cooling plate is in direct contact with the auxiliary layer or with another additional layer, film or foil between the auxiliary layer and the auxiliary cooling plate. According to another example, the main cooling plate is in direct solid-state contact with the auxiliary layer or with an additional layer, film or foil on the side of the auxiliary layer opposite the semiconductor substrate, and the auxiliary cooling plate is in direct contact Infineon Technologies AG 2024P07160 WO

[0070] 12 with the semiconductor substrate or with another additional layer, film or foil between the semiconductor substrate and the auxiliary cooling plate.

[0071] The auxiliary cooling plate may include two parallel plate portions and a coolant duct formed along an interface between two plate portions. Each of the plate portions may include a main part formed from an elementary metal, e.g. copper Cu or aluminum Al, a metal compound or a metal alloy. The auxiliary cooling plate is in a suspension configuration when the main cooling plate is a support configuration. The auxiliary cooling plate is in a support configuration when the main cooling plate is a suspension configuration.

[0072] In the latter case bringing the auxiliary cooling plate into direct contact with the solid substrate composite may include placing the solid substrate composite on an auxiliary cooling surface of the auxiliary cooling plate and lowering the main cooling plate in direction of the solid substrate composite until the main cooling surface is in solid-state contact with the solid substrate composite. The solid substrate composite is clamped between the main cooling surface of the main cooling plate and the auxiliary cooling surface of the auxiliary cooling plate.

[0073] The auxiliary cooling plate can be in direct solid-state contact with the solid substrate composite during the complete cooling period or at least for a part of the cooling period. Cooling the auxiliary cooling plate may include feeding a coolant, e.g. liquid nitrogen N2, into the coolant duct in response to a control signal received from a control unit. The coolant flow may start before the cooling period, simultaneously with the cooling period, or after beginning of the cooling period. The coolant flow can end before the end of the cooling period, simultaneously with the cooling period, or after the cooling period. The coolant flow through the coolant duct of the auxiliary cooling plate may be constant or may vary with time.

[0074] According to an example, the method may further include directly applying mechanical vibrations to the auxiliary cooling plate during and / or after the cooling period at least until the first substrate portion is cleaved from the second substrate portion.

[0075] The mechanical vibrations may include a sequence of pulses and / or oscillations. The auxiliary cooling plate may vibrate along a vertical axis orthogonal to the cooling surface and / or in a horizontal plane parallel to the cooling surface and / or around a vertical rotational axis through Infineon Technologies AG 2024P07160 WO

[0076] 13 a vertical axis of symmetry of the main cooling plate. The amplitude of the mechanical vibrations may be constant or vary over time. A maximum amplitude of the vibrations of the main cooling plate may be in a range from 10nm to 100pm. A frequency of the pulses and / or oscillations may be constant or vary over time. A maximum frequency of the vibrations of the main cooling plate may be in a range from 1 Hz to 100kHz.

[0077] The mechanical vibrations of the auxiliary cooling plate and the main cooling plate may be applied simultaneously or alternatingly. The mechanical vibrations of the auxiliary cooling plate and the main cooling plate may have the same frequency content and may be applied in-phase or out-of-phase. According to other examples, the mechanical vibrations of the auxiliary cooling plate and the main cooling plate have different frequency contents. The maximum amplitudes of the mechanical vibrations of the auxiliary cooling plate and the main cooling plate may be equal or different.

[0078] Another example of the present disclosure relates to another method of splitting a semiconductor substrate. The method may include forming a release layer in a semiconductor substrate, wherein the semiconductor substrate may include a first substrate portion between a first surface and the release layer and a second substrate portion between the release layer and a second surface opposite the first surface. An auxiliary layer may be formed on the first surface, wherein the auxiliary layer and the semiconductor substrate may have different coefficients of thermal expansion. A main cooling plate may be brought into contact with a solid substrate composite including the semiconductor substrate and the auxiliary layer in a cooling period. A vibration plate may be brought into contact with the solid substrate composite at a side opposite the main cooling plate. The main cooling plate may be cooled in the cooling period, wherein the auxiliary layer is cooled. Mechanical vibrations may be applied to the solid substrate composite by using the vibration plate in and / or after the cooling period, wherein the first substrate portion is cleaved from the second substrate portion.

[0079] For example, the main cooling plate is in direct solid-state contact with the semiconductor substrate or with an additional layer, film or foil on the side of the semiconductor substrate opposite the auxiliary layer, and the vibration plate is in direct contact with the auxiliary layer or with another additional layer, film or foil between the auxiliary layer and the vibration plate. According to another example, the main cooling plate is in direct solid-state contact with the Infineon Technologies AG 2024P07160 WO

[0080] 14 auxiliary layer or with an additional layer, film or foil on the side of the auxiliary layer opposite the semiconductor substrate, and the vibration plate is in direct contact with the semiconductor substrate or with another additional layer, film or foil between the semiconductor substrate and the vibration plate.

[0081] The vibration plate is in a suspension configuration when the main cooling plate is a support configuration. The vibration plate is in a support configuration when the main cooling plate is a suspension configuration. The solid substrate composite is clamped between the main cooling surface of the main cooling plate and a working surface of the vibration plate.

[0082] Applying the mechanical vibrations through the vibration plate may begin with the begin of the cooling period or later, e.g. when the main cooling plate or the auxiliary layer reaches a predetermined temperature. The mechanical vibrations may include a sequence of pulses and / or oscillations. The vibration plate may vibrate along a vertical axis orthogonal to the working surface and / or in a horizontal plane parallel to the working surface and / or around a vertical rotational axis through a vertical axis of symmetry of the vibration plate. The amplitude of the mechanical vibrations may be constant or vary over time. A maximum amplitude of the vibrations of the vibration plate may be in a range from 10nm to 100pm. A frequency of the pulses and / or oscillations may be constant or vary over time. A maximum frequency of the vibrations of the vibration plate may be in a range from 1 Hz to 100kHz.

[0083] By applying the mechanical vibrations during or after the cooling period, a continuous crack surface can develop across the entire cross-section of the semiconductor substrate even at higher temperatures and lower thermomechanical stresses than without vibrations.

[0084] Another example of the present disclosure relates to a substrate splitting apparatus. The substrate splitting apparatus includes a main cooling plate and a vibration excitation source. The main cooling plate includes a main cooling surface and is configured to bring the main cooling surface into direct contact with a solid substrate composite in a cooling period. The vibration excitation source is configured to excite vibrations of the main cooling plate along at least one spatial axis in the cooling period. Infineon Technologies AG 2024P07160 WO

[0085] 15

[0086] According to an example, the vibration excitation source may be configured to excite vibrations of the main cooling plate along a vertical axis orthogonal to the main cooling surface.

[0087] According to an example, the vibration excitation source may include one or more piezo actuators attached to the main cooling plate.

[0088] According to an example, at least one of the piezo actuators may be attached to the main cooling plate on a side opposite to the main cooling surface.

[0089] According to an example, the substrate splitting apparatus may further include a suspension unit configured to suspend the main cooling plate, wherein the vibration excitation source is partly or completely integrated in the suspension unit; or a support unit configured to support the main cooling plate, wherein the vibration excitation source is partly or completely integrated in the support unit.

[0090] According to an example, the substrate splitting apparatus may further include a counter plate including a clamping surface opposite the main cooling surface of the main cooling plate, wherein the main cooling plate and the counter plate are configured to clamp the solid substrate composite between the main cooling surface and the clamping surface in a cooling period.

[0091] According to an example, at least one of the main cooling plate and the counter plate may be moveable along a vertical axis orthogonal to the main cooling surface.

[0092] According to an example, the counter plate may be configured as an auxiliary cooling plate.

[0093] Another example of the present disclosure relates to another substrate splitting apparatus. The substrate splitting apparatus may include a main cooling plate and a vibration plate. The main cooling plate includes a main cooling surface and may be configured to bring the main cooling surface into direct contact with a solid substrate composite for a cooling period. The vibration plate includes an auxiliary surface opposite the main cooling surface of the main cooling plate. The main cooling plate and the vibration plate may be configured to clamp the solid substrate composite between the main cooling surface and the auxiliary surface in the cooling period. Infineon Technologies AG 2024P07160 WO

[0094] 16

[0095] The vibration plate may further be configured to excite vibrations of the solid substrate composite along at least one spatial axis in and / or after the cooling period.

[0096] Fig. 1 A to Fig. 1 D show successive phases of a method of splitting a semiconductor substrate 110. A release layer 115 is formed in the semiconductor substrate 110 by laser irradiation.

[0097] Fig. 1 A shows a semiconductor substrate 110 may be made of single-crystalline silicon carbide SiC. The semiconductor substrate 110 has the form of a cylinder with an approximately planar first surface 111 at one end of the cylinder and an approximately planar second surface 112 at the opposite end. The first surface 111 and the second surface 112 are oriented approximately parallel, e.g. parallel, to each other. The base of the cylinder is a complete circle or a circle with a notch or flat. For example, the semiconductor substrate 110 is a SiC wafer or a SiC puck.

[0098] The laser radiation enters the semiconductor substrate 110 through the first surface 111 and is focused at a predefined distance from the first surface 111. The focused laser radiation locally heats a focal point region in the semiconductor substrate 110 around the focal point, wherein in the focal point region the silicon carbide crystal decomposes. The decomposition products in the focal point region form a modified region 117 containing amorphous silicon and amorphous carbon. The high-temperature decomposition exerts high pressure on the portion of the silicon carbide crystal surrounding the focal point region. The pressure creates subcritical cracks in the part surrounding the modified region 117. The laser radiation is controlled so that a plurality of modified regions 117 are formed adjacent to each other and at the same distance from the first surface 111. The modified regions 117 and the sub-critical cracks originating at or adjacent to the modified regions 117 form the release layer 115.

[0099] The release layer 115 defines a first substrate portion 114 substantially between the first surface 111 and the release layer 115 and a second substrate portion 116 substantially between the release layer 115 and the second surface 112. Each of the first substrate portion 114 and the second substrate portion 116 includes portions of the release layer 115. The first substrate portion 114 and the second substrate portion 116 essentially complement each other to form the semiconductor substrate 110. Infineon Technologies AG 2024P07160 WO

[0100] 17

[0101] An auxiliary layer 120 is placed directly on the first surface 111 . A bonding process provides a strong mechanical connection between the auxiliary layer 120 and the semiconductor substrate 110. The bonding process may involve pressing the auxiliary layer 120 and the semiconductor substrate 110 against each other, a heating treatment, or a combination of both.

[0102] Fig. 1 B shows the auxiliary layer 120 bonded onto the first surface 111 of the semiconductor substrate 110. The bonding process may result in the creation of chemical bonds between the semiconductor substrate 110 and the auxiliary layer 120. The auxiliary layer 120 is based on PDMS containing a filler for high thermal conductivity. The CTE of the auxiliary layer 120 is at least 30 times or 50 times higher than the CTE of the semiconductor substrate 110. The auxiliary layer 120 and the semiconductor substrate 110 form a solid substrate composite 100.

[0103] The solid substrate composite 100 is placed directly on a main cooling surface 211 of a main cooling plate 210 in support configuration.

[0104] In Fig. 1C, the main cooling plate 210 includes a first main plate portion 214 with the main cooling surface 211 and a second main plate portion 216, wherein the first main plate portion 214 and the second main plate portion 216 have the same lateral dimensions and are in direct contact with each other along a planar interface. Each of the plate portions 214, 216 includes a main part formed from copper Cu or a copper alloy. The main cooling plate 210 is heavier than 1 kg, e.g., heavier than 5kg or 10kg. The main cooling surface 211 and a further part of the surface of the first main plate portion 214 may be covered with diamond-like carbon (DLC). The main cooling surface 211 is directed upwards and aligned in a plane orthogonal to the direction of gravity. A main plate coolant duct 215 is formed along the interface between the plate portions 214, 216. The main plate coolant duct 215 may form a flat, horizontal spiral duct connecting a vertical main plate coolant feeding duct 218 and a vertical main plate coolant discharge duct 219. The vertical main plate coolant feeding duct 218 and the vertical main plate coolant discharge duct 219 pass through the second main plate portion 216. One or more column-like support structures (not illustrated) carry and stabilize the main cooling plate 210 in a process chamber.

[0105] The solid substrate composite 100 is placed with the second surface 112 of the semiconductor portion 110 oriented to the main cooling surface 211 . The placement takes place at an ambient Infineon Technologies AG 2024P07160 WO

[0106] 18 temperature TA of about 20° Celsius. Then the solid substrate composite 100 may be clamped between the main cooling surface 211 and a substrate holder, e.g., between the main cooling surface 211 and a clamping surface of a counter plate (not illustrated).

[0107] Liquid nitrogen N2 is fed through the main plate coolant feeding duct 218 into the main plate coolant duct 215. The liquid nitrogen N2 cools the main cooling plate 210 and the solid substrate composite 110 with the auxiliary layer 120 and the semiconductor substrate 110. Gaseous N2 leaves the main plate coolant duct 215 through the main plate coolant discharge duct 219. Mechanical vibrations are directly applied to the main cooling plate 210 at the same time when the solid substrate composite 110 is actively cooled down and liquid nitrogen N2 flows through the main plate coolant duct 215, after the auxiliary layer 120 reaches a predetermined temperature, or after the inflow of liquid nitrogen ends.

[0108] Fig. 1 D shows the vibrating main cooling plate 210. The arrows indicate possible directions of movement for the vibrating main cooling plate 210. The vibration may move the main cooling plate 210 along a vertical direction parallel to the direction of gravity, in a horizontal plane orthogonal to the vertical direction, and / or around a vertical axis of symmetry of the main cooling plate 210. The amplitude of the mechanical vibrations may be constant or vary over time. A maximum amplitude of the vibrations of the main cooling plate 210 may be in a range from 10nm to 100pm. A frequency of the pulses and / or oscillations may be constant or vary over time. A maximum frequency of the vibrations of the main cooling plate 210 may be in a range from 1 Hz to 100kHz.

[0109] The comparatively high difference in CTE in combination with the strong bond between the semiconductor substrate 110 and the auxiliary layer 120 creates high thermomechanical stresses in the auxiliary layer 120 and the semiconductor substrate 110. The subcritical cracks created during formation of the release layer 115 in the semiconductor substrate 110 can propagate along main crystal planes. The mechanical vibrations support the crack propagation by additionally stressing the release layer 115. A continuous crack surface can develop across the entire cross-section of the semiconductor substrate 110 even at higher temperatures and lower thermomechanical stresses than without vibrations. The first substrate portion 112 reliably cleaves from the second substrate portion 114 even for a small thickness of the Infineon Technologies AG 2024P07160 WO

[0110] 19 semiconductor substrate 110 of less than 2mm, e.g. less than 1.5mm. The cleaving may take place at a temperature lower than a glass transition temperature Tg of the auxiliary layer 120.

[0111] Fig. 2A to Fig. 2B show successive phases of a method of splitting a semiconductor substrate 110 using a substrate splitting apparatus 200 that includes a counter plate 270 in support configuration and a main cooling plate 210 in suspension configuration.

[0112] The counter plate 270 includes a clamping surface 271 facing against the direction of gravity. The clamping surface 271 may be planar or may include a recess matching the horizontal dimensions of the solid substrate composite 100. A feeding apparatus may place the solid substrate composite 100 on the clamping surface 271 when the counter plate 270 and the main cooling plate 210 are fixed at a loading distance to each other which is greater than the vertical extension of the solid substrate composite 100.

[0113] Fig. 2A shows the substrate splitting apparatus 200 in the loading configuration with the main cooling plate 210 placed directly above the counter plate 270 and with the main cooling surface 211 of the main cooling plate 210 and the clamping surface 271 of the counter plate 270 having the loading distance. The solid substrate composite 100 is placed on the clamping surface 271. The counter plate 270 may be configured as auxiliary cooling plate, as vibration plate, as a plate combining cooling and vibration functions, or as simple holder.

[0114] The counter plate 270 is moved upwards along the vertical direction and / or the main cooling plate 210 is lowered along the vertical direction until the solid substrate composite 100 is clamped between the main cooling surface 211 and the clamping surface 271. The main cooling plate 210 is cooled and mechanically excited to vibrate.

[0115] Fig. 2B shows the substrate splitting apparatus 200 in a working configuration with solid-state contacts between the main cooling plate 210 and the solid substrate composite 100 and between the counter plate 270 and the solid substrate composite 100. The main cooling plate 210 cools the solid substrate composite 100 and at the same time vibrates. Alternatively, the main cooling plate 210 may alternatingly vibrate and further cool down the solid substrate composite 100, and / or may vibrate after cooling the solid substrate composite 100 to a target temperature, which may be lower than a glass transition temperature of the auxiliary layer 120. Infineon Technologies AG 2024P07160 WO

[0116] 20

[0117] In Fig. 3, the solid substrate composite 100 includes a first additional layer, film or foil 130 formed on a surface of the auxiliary layer 120 opposite the semiconductor substrate 110. The first additional layer, film or foil 130 may be homogenous or may include two or more sublayers, wherein at least two of the sublayers have different material configurations, e.g., different compositions. The counter plate 270 and the first additional layer, film or foil 130 form a solid- state contact. The first additional layer, film or foil 130 may be or include a dicing tape.

[0118] In addition, the solid substrate composite 100 includes a second additional layer, film or foil 140 formed on the second surface 112 of the semiconductor substrate 110. The second additional layer, film or foil 140 may be homogenous or may include two or more sublayers, wherein at least two of the sublayers have different material configurations, e.g., different compositions. The thermal conductivity of the second additional layer, film or foil 140 is in the same order of magnitude as the thermal conductivity of the semiconductor substrate 110 or higher. The main cooling plate 210 and the second additional layer, film or foil 140 form a solid- state contact. The second additional layer, film or foil 140 may be or include a protective tape.

[0119] In other examples, the solid substrate composite 100 includes only one of the first additional layer, film or foil 130 and the second additional layer, film or foil 140.

[0120] The substrate splitting apparatus 200 includes a vibration excitation source with several piezo actuators 310 (e.g. two or more) mounted at a side of the main cooling plate 210 opposite the counter plate 270. Each piezo actuator 310 includes a housing 312 fixed to the second main plate portion 216, a piezo element 314 contracting and expanding in the housing 312 along the vertical direction in response to a varying electrical control voltage, and a piston 316 converting the contraction / expansion of the piezo element 314 into a vertical force acting on the main cooling plate 210.

[0121] Fig. 4A shows a substrate splitting apparatus 200 that includes a main cooling plate 210 in suspension configuration and an auxiliary cooling plate 220 in support configuration. The main cooling plate 210 may have any of the configurations described above. In addition, a coating 217, e.g., a DLC coating may cover the main cooling surface 211 and the outer surface of the Infineon Technologies AG 2024P07160 WO

[0122] 21 first main plate portion 214. The auxiliary cooling plate 220 may have a similar configuration as the main cooling plate 210.

[0123] The auxiliary cooling plate 220 includes a first auxiliary plate portion 224 providing an auxiliary cooling surface 221 and a second auxiliary plate portion 226, wherein the first auxiliary plate portion 224 and the second auxiliary plate portion 226 have the same lateral dimensions and are in direct contact with each other along a planar interface. Each of the plate portions 224, 226 includes a main part formed from copper Cu or a copper alloy. The auxiliary cooling surface 221 is directed upwards and aligned in a plane orthogonal to the direction of gravity. An auxiliary plate coolant duct 225 is formed along the interface between the plate portions 224, 226. The auxiliary plate coolant duct 225 may form a flat, horizontal spiral duct connecting a vertical auxiliary plate coolant feeding duct 228 and a vertical auxiliary plate coolant discharge duct 229. The vertical auxiliary plate coolant feeding duct 228 and the vertical auxiliary plate coolant discharge duct 229 pass through the second auxiliary plate portion 226. One or more column-like support structures (not illustrated) carry and stabilize the auxiliary cooling plate 220 in a process chamber. Auxiliary actuators 320 mounted on the side of the auxiliary cooling plate 220 opposite the main cooling plate 210 are configured to excite vibrations of the auxiliary cooling plate 220 along the vertical direction. The auxiliary actuators may be electromechanical actuators or piezo actuators, by way of example.

[0124] The solid substrate composite 100 includes a first additional layer, film or foil 130 configured as dicing tape stretched in a polygonal or round frame 135. A handler unit may use the frame 135 to load the substrate splitting apparatus 200 with the solid substrate composite 100, wherein the handler unit places the frame 135 in such a way that the first additional layer, film or foil 130 rests on the auxiliary cooling plate 220 as illustrated in Fig. 4A.

[0125] The main cooling plate 210 moves downwards such that the weight force of the main cooling plate 210 clamps the solid substrate composite 100 between the main cooling surface 211 and the auxiliary cooling surface 221 for a working configuration illustrated in Fig. 4B.

[0126] The main cooling plate 210 is in direct solid-state contact with the semiconductor substrate 110. The auxiliary cooling plate 220 is in direct solid-state contact with the first additional layer, film or foil 130. Infineon Technologies AG 2024P07160 WO

[0127] 22

[0128] In the cooling period, a coolant, e.g. liquid nitrogen N2, is fed into the coolant ducts 215, 225 in response to a control signal received from a control unit. The coolant flow may start before the cooling period, simultaneously with the cooling period, or after begin of the cooling period. The coolant flow can end before the end of the cooling period, simultaneously with the cooling period, or after the cooling period. The coolant flow through the coolant ducts 215, 225 may be constant or may vary with time. The piezo actuators 310 excite vibrations of the main cooling plate 210 along the vertical direction. The auxiliary actuators 320 excite vibrations of the auxiliary cooling plate 220 along the vertical direction. The piezo actuators 310 and the auxiliary actuators 320 may work in-phase or out-of-phase during the cooling period.

[0129] Fig. 5 shows the working configuration of another substrate splitting apparatus 200. The main cooling plate 210 may be configured as vibration-free unit, which is moveable along the vertical axis to clamp and release a solid substrate composite 100 and which is fixed in the rest, in particular during the cooling period. The solid substrate composite 100 is clamped between the main cooling surface 211 of the main cooling plate 210 and an auxiliary surface 261 of a vibration plate 260. The main cooling plate 210 is cooled in the cooling period. The vibration plate 260 applies mechanical vibrations to the solid substrate composite 100 in and / or after the cooling period until the first substrate portion 112 is cleaved from the second substrate portion 114.

[0130] According to another example, the main cooling plate 210 has any of the configurations described above and vibrations of the main cooling plate 210 and mechanical vibrations generated by the vibration plate 260 act on the solid substrate composite 100 in combination.

[0131] Fig. 6 shows a substrate splitting apparatus 200 with a main cooling plate 210 in suspension configuration. The main cooling plate 210 includes a main cooling surface 211 directed downwards. The substrate splitting apparatus 200 further includes a substrate holder 250 placed below the main cooling surface 211. The substrate holder 250 is configured to fix a solid substrate composite as described above. The substrate splitting apparatus 200 is configured to move at least one of the main cooling plate 210 and the substrate holder 250 along a vertical direction such that the main cooling surface 211 is pressed against the solid substrate composite. Infineon Technologies AG 2024P07160 WO

[0132] 23

[0133] The main cooling plate 210 has a first main plate portion 214, a second main plate portion 216, a main plate coolant duct 215, a main plate coolant feeding duct 218 and a main plate coolant discharge duct 219 as described above, e.g., with reference to Fig. 1 C. A multi-part vibration excitation source 300 mounted on the main cooling plate 210 is configured to directly excite vibrations of the main cooling plate 210 along the vertical direction, in the horizontal plane, and / or around a vertical axis. The vibration excitation source 300 may include electromagnetic actuators and / or piezo actuators. The substrate holder 250 may support the solid substrate composite from the underside and / or from the lateral side.

[0134] In Fig. 7, the main cooling plate 210 is in support configuration. The main cooling surface 211 is directed upwards. The substrate holder 250 is placed above the main cooling surface 211. A multi-part vibration excitation source 300 is integrated in a support unit 290 that supports the main cooling plate 210. In another example, the multi-part vibration excitation source 300 is mounted outside the support unit 290.

[0135] In Fig. 8, the substrate holder is configured as flat counter plate 270 with a planar clamping surface 271 directed upwards. The material of the counter plate 270 has a thermal conductivity that is by at least one order of magnitude lower than the thermal conductivity of the main parts of the main cooling plate 210. The vibration excitation source includes piezo actuators 310 attached to the main cooling plate 210 at a side opposite the counter plate 270. At least one of the main cooling plate 210 and the counter plate 270 is moveable along the vertical direction such that in a working configuration a solid substrate composite can be clamped between the main cooling surface 211 and the clamping surface 271 for a cooling period.

[0136] In Fig. 9, the piezo actuators 310 are integrated in suspension units 280 at which the main cooling plate 210 suspends.

[0137] Fig. 10 and Fig. 11 show substrate splitting apparatuses 200 whose counter plates are configured as auxiliary cooling plates 220. Each auxiliary cooling plate 220 includes a first auxiliary plate portion 224, a second auxiliary plate portion 226, a main plate coolant duct 225, an auxiliary plate coolant feeding duct 228 and an auxiliary plate coolant discharge duct 229 as described above, e.g., with reference to Fig. 4A. Infineon Technologies AG 2024P07160 WO

[0138] 24

[0139] In Fig. 10, the auxiliary cooling plate 220 is not directly excited to vibrate but may be indirectly excited to vibrate by the vibrating main cooling plate 210 via the clamped solid substrate composite.

[0140] In Fig. 11 , auxiliary actuators 320 are mounted on the auxiliary cooling plate 220 to directly excite vibrations of the auxiliary cooling plate 220. In another example, the auxiliary actuators 320 may be integrated in a support structure for the auxiliary cooling plate 220 similar as illustrated in Fig. 7 for a multi-part vibration excitation source 300 integrated in the support unit for the main cooling plate 210.

[0141] Fig. 12 shows a substrate splitting apparatus 200 with a main cooling plate 210 that is not directly excited to vibrate, and a vibration plate 260. At least one of the main cooling plate 210 and the vibration plate 260 is moveable along the vertical direction to clamp and release a solid substrate composite between the main cooling surface 211 of the main cooling plate 210 and an auxiliary surface 261 of the vibration plate 260. The main cooling plate 210 is coolable. The vibration plate 260 rests on a vibrating column 265. The vibrating column 265 is configured to apply mechanical vibrations to the vibration plate 260 in and / or after the cooling period until. The vibrating column 265 may excite vibrations of the vibration plate and the clamped solid semiconductor composite along the vertical direction, in the horizontal plane, and / or around a vertical axis of the vibrating column 265.

[0142] Though the illustrated examples show substrate splitting apparatuses oriented along a vertical direction parallel to the direction of gravity, other examples include substrate splitting apparatuses oriented along a direction tilted to the vertical direction, e.g., in the horizontal plane.

[0143] The embodiments of the independent claims share the features of cooling and letting vibrate a solid substrate composite at the same time or at least in close temporal relationship, and without tool change.

[0144] Although specific examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations Infineon Technologies AG 2024P07160 WO

[0145] 25 may be substituted for the specific examples shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.

[0146] It should be noted that the methods and apparatuses including its preferred embodiments as outlined in the present document may be used stand-alone or in combination with the other methods and apparatuses disclosed in this document. In addition, the features outlined in the context of an apparatus are also applicable to a corresponding method, and vice versa. Furthermore, all aspects of the methods and apparatuses outlined in the present document may be arbitrarily combined. In particular, the features of the claims may be combined with one another in an arbitrary manner.

[0147] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and systems. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and embodiments outlined in the present document are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the proposed methods and systems. Furthermore, all statements herein providing principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims

Infineon Technologies AG 2024P07160 WO26CLAIMS1. A method of splitting a semiconductor substrate, comprising: forming a release layer (115) in a semiconductor substrate (110), wherein the semiconductor substrate (110) comprises a first substrate portion (114) between a first surface (111 ) and the release layer (115) and a second substrate portion (116) between the release layer (115) and a second surface (112) opposite the first surface (111); forming an auxiliary layer (120) on the first surface (111), the auxiliary layer (120) and the semiconductor substrate (110) having different coefficients of thermal expansion; bringing a main cooling plate (210) into contact with a solid substrate composite (100) comprising the semiconductor substrate (110) and the auxiliary layer (120) in a cooling period; cooling the main cooling plate (210) in the cooling period, wherein the auxiliary layer (120) is cooled; and applying mechanical vibrations directly to the main cooling plate (210) in the cooling period, wherein the first substrate portion (114) is cleaved from the second substrate portion (116).

2. The method according to the preceding claim, wherein the auxiliary layer (120) comprises a material exhibiting a glass transition at a glass transition temperature and the auxiliary layer (120) is cooled to a temperature below the glass transition temperature.

3. The method according to any of the preceding claims, wherein the release layer (115) is formed by locally modifying a composition and / or structure of the semiconductor substrate (110).

4. The method according to any of the preceding claims, wherein the main cooling plate (210) is brought into direct contact with the auxiliary layer (120) or the semiconductor substrate (110).Infineon Technologies AG 2024P07160 WO275. The method according to any of the preceding claims, wherein the mechanical vibrations are applied to a side of the main cooling plate (210) opposite the solid substrate composite (100).

6. The method according to any of the preceding claims, wherein the mechanical vibrations are generated by one or more vibration excitation sources (300) attached to the main cooling plate (210).

7. The method according to any of the preceding claims, wherein the mechanical vibrations are generated after the auxiliary layer (120) has reached the target temperature.

8. The method according to any of the preceding claims, further comprising: bringing an auxiliary cooling plate (220) into direct contact with a side of the solid substrate composite (100) opposite the main cooling plate (210) and cooling the auxiliary cooling plate (220).

9. The method according to the preceding claim, further comprising: applying mechanical vibrations directly to the auxiliary cooling plate (220) during and / or after the cooling period at least until the first substrate portion (114) is cleaved from the second substrate portion (116).

10. A method of splitting a semiconductor substrate, comprising: forming a release layer (115) in a semiconductor substrate (110), wherein the semiconductor substrate (110) comprises a first substrate portion (114) between a first surface (111 ) and the release layer (115) and a second substrate portion (116) between the release layer (115) and a second surface (112) opposite the first surface (111); forming an auxiliary layer (120) on the first surface (111), the auxiliary layer (120) and the semiconductor substrate (110) having different coefficients of thermal expansion;Infineon Technologies AG 2024P07160 WO28 bringing a main cooling plate (210) into contact with a solid substrate composite (100) comprising the semiconductor substrate (110) and the auxiliary layer (120) in a cooling period; bringing a vibration plate (260) into contact with the solid substrate composite (100) at a side opposite the main cooling plate (210); cooling the main cooling plate (210) in the cooling period, wherein the auxiliary layer (120) is cooled; and applying mechanical vibrations to the solid substrate composite (100) by using the vibration plate (260) in and / or after the cooling period, wherein the first substrate portion (114) is cleaved from the second substrate portion (116).

11. A substrate splitting apparatus, comprising: a main cooling plate (210) comprising a main cooling surface (211), the main cooling plate (210) being configured to bring the main cooling surface (211) into direct contact with a solid substrate composite (100) in a cooling period; and a vibration excitation source (300) configured to excite vibrations of the main cooling plate (210) along at least one spatial axis in the cooling period.

12. The substrate splitting apparatus according to the preceding claim, wherein the vibration excitation source (300) is configured to excite vibrations of the main cooling plate (210) along a vertical axis orthogonal to the main cooling surface (211).

13. The substrate splitting apparatus according to any of the two preceding claims, wherein the vibration excitation source (300) comprises one or more piezo actuators(310) attached to the main cooling plate (210).

14. The substrate splitting apparatus according to the preceding claim, wherein at least one of the piezo actuators (310) is attached to the main cooling plate (210) on a side opposite to the main cooling surface (211).

15. The substrate splitting apparatus according to any of the four preceding claims, further comprising:Infineon Technologies AG 2024P07160 WO29 a suspension unit (280) configured to suspend the main cooling plate (210), wherein the vibration excitation source (300) is partly or completely integrated in the suspension unit (280); or a support unit (290) configured to support the main cooling plate (210), wherein the vibration excitation source (300) is partly or completely integrated in the support unit (290).

16. The substrate splitting apparatus according to any of the five preceding claims, further comprising: a counter plate (270) comprising a clamping surface (271) opposite the main cooling surface (211) of the main cooling plate (210), wherein the main cooling plate (210) and the counter plate (270) are configured to clamp the solid substrate composite (100) between the main cooling surface (211) and the clamping surface (271) in a cooling period.

17. The substrate splitting apparatus according to the preceding claim, wherein at least one of the main cooling plate (210) and the counter plate (270) is moveable along a vertical axis orthogonal to the main cooling surface (211 ).

18. The substrate splitting apparatus according to any of the two preceding claims, wherein the counter plate (270) is configured as an auxiliary cooling plate (220).

19. A substrate splitting apparatus, comprising: a main cooling plate (210) comprising a main cooling surface (211), the main cooling plate (210) being configured to bring the main cooling surface (211) into direct contact with a solid substrate composite (100) in a cooling period; a vibration plate (260) comprising an auxiliary surface (261) opposite the main cooling surface (211) of the main cooling plate (210), wherein the main cooling plate (210) and the vibration plate (260) are configured to clamp the solid substrate composite (100) between the main cooling surface (211) and the auxiliary surface (261) in a cooling period, and wherein the vibration plate (260) is configured to excite vibrations of the solid substrate composite (100) along at least one spatial axis in and / or after the cooling period.

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