Apparatus and method for splitting semiconductor wafer

Abstract

An apparatus for holding a semiconductor workpiece during a splitting process is disclosed. The device includes a polymer and a frame. The frame is attached to and surrounds the polymer. The polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature, and is elastic when having a temperature above the critical temperature. The polymer includes a first region having a surface to which the semiconductor workpiece may be attached.

Description

Background Art

[0001] Wafer costs account for a significant portion of the total production costs of silicon carbide (SiC) semiconductor devices. Wafers are typically obtained from a solid material in bulk form, known as a boule or ingot. For example, pieces can be obtained from such an ingot (or boule) using a sawing process. These pieces can already form wafers, or the obtained wafers can be further divided until they have the desired thickness for the wafers to be produced. In the sawing process, a wire saw (e.g., made of diamond) is typically used, which can result in a loss of up to 50% of the original solid material, known as "kerf loss," which can be disadvantageous in the case of expensive starting solid material.

[0002] Furthermore, the sawing operation can cause damage to the wafer surface, which may require remediation, for example, through additional process steps for surface treatment, such as grinding or polishing. Alternatively, splitting methods can be used to divide the ingot into wafers and smaller ingots (i.e., wafers can be split directly from the ingot), and / or to split a thick wafer into two thinner wafers. In one example, polymer films are used to facilitate splitting. However, handling polymer films can be challenging in some applications. Summary of the Invention

[0003] According to an embodiment, an apparatus for holding a semiconductor workpiece during a cleavage process includes a polymer and a frame. The semiconductor workpiece may include or may be a semiconductor ingot or a semiconductor wafer. The frame may be connected to the polymer. The frame surrounds the polymer. The polymer may be configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when at a temperature above the critical temperature. The polymer includes a first region having a surface to which the semiconductor workpiece may be attached.

[0004] According to an embodiment, the frame and / or the polymer comprises at least one attachment element, wherein the polymer is directly attached to the frame via the at least one attachment element.Thereby, the polymer and the frame can be connected.

[0005] According to an embodiment, the apparatus may further include a foil, wherein the foil is fixedly attached to the polymer and the frame, thereby connecting the polymer and the frame. The frame may be a wafer ring (sometimes also referred to as a "wafer frame"), and the foil may be a dicing foil. The foil may be attached to the polymer at a surface of the polymer opposite to a surface to which the semiconductor workpiece may be attached.

[0006] According to some embodiments, the thickness of the polymer in the first region is at least 2 mm, or at least 2.5 mm. For example, the thickness of the polymer in the first region may be between at least 2 mm and at most 4 mm, or between at least 2.5 mm and at most 3.5 mm.

[0007] In some embodiments, the polymer is directly attached to the frame, thereby connecting the polymer and the frame.

[0008] According to an embodiment, the polymer comprises a second region which does not overlap with the first region of the polymer and which surrounds the first region of the polymer.

[0009] In some embodiments, the polymer surface to which the semiconductor workpiece can be attached (the so-called "functional surface") can have a surface roughness of at least 0.1 μm and at most 2 μm (or at least 0.1 μm and at most 1 μm or at least 0.2 μm and at most 0.8 μm). The surface roughness can generally be the arithmetic mean height (Sa). The polymer surface opposite the functional surface (e.g., the back surface of the polymer and / or the surface to which the foil is attached (if applicable)) can have the same surface roughness as the functional surface, or can have a higher surface roughness, for example, the surface roughness of the polymer surface opposite the functional surface can be at least 1 μm and at most 10 μm (or at least 2 μm and at most 8 μm or at least 2 μm and at most 5 μm). If the polymer includes a second region, the polymer surface in the second region adjacent to the functional surface can have the same surface roughness as the functional surface, or can have a higher surface roughness. For example, the surface roughness of the polymer surface in the second zone adjoining the functional surface may be at least 1 μm and at most 10 μm (or at least 2 μm and at most 8 μm or at least 2 μm and at most 5 μm).

[0010] In some embodiments, the surface of the second zone is substantially annular or loop-shaped. The inner circle of the ring can be given by the surface of the first zone. The outer circle diameter of the ring can be at least 16 cm, at least 18 cm, or at least 22 cm.

[0011] Typically, the diameter of the polymer, such as the outer diameter of the second region or the diameter of the first region in the absence of the second region, can be at least 95%, or at least 105%, and / or at most 110%, or at most 120% of the diameter of the semiconductor workpiece. In some examples, the diameter of the polymer can be at least 3 mm, or at least 4 mm, or at least 5 mm larger than the diameter of the semiconductor workpiece.

[0012] In an embodiment, the frame includes a flexible ring, wherein the flexible ring has a substantially circular shape with a first diameter. In one or more embodiments, the flexible ring includes three or more ring elements and corresponding three or more flexible attachment elements, each flexible attachment element connecting two corresponding ring elements of the three or more ring elements to each other to form the flexible ring. When a force directed toward a center of the flexible ring is applied to the flexible ring, the flexible attachment elements contract such that the flexible ring has a substantially circular shape with a second diameter, the second diameter being smaller than the first diameter.

[0013] In an embodiment, the frame further includes an outer ring. The flexible ring can be removably attached to the outer ring. In this context, "removably attached" can refer to a connection that can be released (e.g., mechanically released) without destroying the outer ring and the flexible ring.

[0014] In some embodiments, an apparatus for attaching a polymer to a semiconductor workpiece is used during a cleaving process.

[0015] According to an embodiment, a method for splitting a semiconductor workpiece includes attaching the semiconductor workpiece to a first region of a surface of an apparatus. Optionally, a separation region may be formed within the semiconductor workpiece. The apparatus includes a polymer and a frame, wherein the frame is connected to and surrounds the polymer. The polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when at a temperature above the critical temperature. The polymer includes the surface. The method further includes cooling the workpiece and the first region of the apparatus together to a temperature below the critical temperature.

[0016] In an embodiment, the surface of the polymer comprises a second region that does not overlap with the first region of the surface.During cooling, at least a portion of the second region is maintained at a temperature above the critical temperature.

[0017] In one or more embodiments, the semiconductor workpiece is attached to the apparatus such that an outer surface of the ingot is placed on the apparatus at a closer distance to a separation region within the semiconductor workpiece than a surface of the semiconductor workpiece opposite the outer surface.

[0018] In an embodiment, an apparatus for holding a semiconductor workpiece during a cleaving process includes a polymer and a frame, wherein the frame is directly connected to and surrounds the polymer, the polymer being configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when having a temperature above the critical temperature, wherein the polymer includes a surface to which the semiconductor workpiece can be attached, and wherein the polymer has a diameter of at least 16 cm or at least 18 cm.

[0019] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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 designate similar or identical elements. The elements of the drawings are not necessarily to scale relative to each other. Features of the various illustrated examples may be combined unless they exclude each other.

[0021] Figures 1A to 1E Illustrated are cross-sectional views of a semiconductor wafer during different stages of a wafer splitting process according to an embodiment.

[0022] Figure 2 A portion of a separation region formed in a semiconductor substrate is illustrated and includes micro cracks at least partially disconnected from each other in the separation region.

[0023] Figure 3A Shown is a graph of storage modulus versus temperature for a polymer used during a wafer splitting process, and the polymer does not contain a filler.

[0024] Figure 3B The diagram shows Figure 3A A graph of storage modulus versus temperature for a polymer containing one or more fillers.

[0025] Figure 4A Illustrated is a side view of an apparatus that may be used during a wafer splitting process according to an embodiment.

[0026] Figure 4B and Figure 4C Pictured Figure 4A A top view of an embodiment of the device is shown in FIG.

[0027] Figure 5A Illustrated is one side of an apparatus that may be used during a wafer splitting process according to an embodiment.

[0028] Figure 5B Illustrated is a side view of an apparatus that may be used during a wafer splitting process according to an embodiment.

[0029] Figure 5C Pictured Figure 5A and Figure 5B Top view of the device shown in .

[0030] Figure 6 Illustration about Figures 4A to 5C Another embodiment of the frame is shown in .

[0031] Figure 7 The diagram shows the Figures 4A to 6 The device shown in FIG.

[0032] Figure 8 Illustration of where you can use Figures 4A to 7 method of the device. DETAILED DESCRIPTION

[0033] It is noted that modifications and other embodiments of the disclosed invention(s) will occur to those skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it should be understood that the invention(s) are not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0034] The present disclosure relates to processes for splitting semiconductor workpieces and apparatus that can be used in such processes. The semiconductor workpiece can be or can include a semiconductor crystal blank (also referred to as an "ingot") or a semiconductor wafer. While the focus is on workpieces including or consisting of SiC as a material (and SiC devices produced using SiC wafers), the embodiments described herein are not intended to be limited to SiC wafers and can be used with other semiconductor wafer technologies, such as silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), sapphire, and the like.

[0035] In some embodiments, the cleaving techniques described herein can be applied to cleave semiconductor wafers from a semiconductor ingot. The cleaving techniques described herein can be applied to cleave semiconductor wafers from a semiconductor ingot by forming a separation region within the semiconductor ingot, the separation region having at least one altered physical property that increases thermomechanical stress within the separation region relative to the remainder of the semiconductor ingot. For example, by focusing laser radiation at a target location within the semiconductor ingot, the thermomechanical stress within the separation region can be increased. An external force can then be applied to the semiconductor ingot, causing at least one crack to propagate along the separation region and cleave the wafer from the semiconductor ingot. For example, the external force can be applied to the semiconductor ingot by applying a polymer to the semiconductor ingot, the polymer having a CTE that differs from the CTE of the semiconductor ingot. The polymer and the semiconductor ingot are subjected to a temperature process, during which the polymer applies mechanical stress to the semiconductor ingot. This process can be applied multiple times to produce multiple wafers from a single semiconductor ingot.

[0036] In other embodiments, device structures are produced in a base semiconductor wafer, and the base wafer is subsequently split into a thinner device wafer including the device structures and an even thinner recycled wafer. The recycled wafer can be processed, and additional devices can be produced within the recycled wafer.

[0037] The wafer splitting technique described herein includes at least two main steps: (i) forming a separation region within a semiconductor workpiece (e.g., a crystal ingot or wafer), wherein the separation region has at least one altered physical property that increases thermomechanical stress within the separation region relative to the remainder of the semiconductor workpiece; and (ii) applying an external force to the semiconductor workpiece such that at least one crack propagates along the separation region and the semiconductor wafer is split from the semiconductor workpiece (or the semiconductor workpiece is split into two separate wafers, or a thinner semiconductor wafer is split from the semiconductor workpiece).

[0038] In some embodiments, forming the separation region includes forming microcracks within the separation region that are at least partially disconnected from one another. In response to an external force applied to a semiconductor workpiece (such as an ingot or a semiconductor wafer), the microcracks connect to one another, thereby forming at least one crack that propagates along the separation region and splits the semiconductor wafer from the ingot (or splits the semiconductor wafer into two separate pieces). The external force applied to the semiconductor workpiece may involve the application of a polymer layer.

[0039] Next, various embodiments of a semiconductor splitting process are described. The following disclosure is directed to splitting a semiconductor wafer into two separate semiconductor wafers. Unless otherwise indicated, the same process can be applied to splitting a semiconductor wafer from a crystal ingot. In this case, the semiconductor wafer 100 shown in the following figures corresponds to the crystal ingot.

[0040] Figures 1A to 1E The diagram illustrates cross-sectional views of a semiconductor workpiece 100 during different stages of a cleaving process according to an embodiment. As explained above, the semiconductor workpiece 100 can be any type of wafer used to produce semiconductor devices. For example, the semiconductor workpiece can be a SiC wafer or SiC ingot, such as 4H-SiC, and can have a thickness (T_wafer) that can vary depending on the wafer diameter. Typically, 4-inch and 6-inch (150 mm) SiC wafers have a thickness of 350 μm (micrometers), with an accuracy of, for example, up to ±40 μm or up to ±25 μm. For larger SiC wafer diameters (e.g., 200 mm and / or 8-inch SiC wafers), the thickness can be higher. For example, a 200 mm wafer can have a thickness of 500 μm (±40 μm or ±25 μm). As explained above, the wafer cleaving process described herein can also be applied to other SiC polytypes and / or other semiconductor materials (e.g., Si, GaAs, GaN, sapphire, etc.), with corresponding adaptation of the process parameters.

[0041] Figure 1A is an optional processing step that may not be present according to the present disclosure. In particular, Figure 1AThe semiconductor workpiece 100 is shown after forming one or more epitaxial layers 102 thereon, forming a device structure 104 in the one or more epitaxial layers 102, forming a metallization layer and / or a passivation layer 106 (e.g., at least one passivation layer) above the device structure 104, and attaching a carrier 108 to the semiconductor workpiece 100 using the one or more epitaxial layers 102. Layer 106 is shown as a continuous layer in the cross-sectional view, but may instead be discontinuous. For example, in the case of a passivation layer, layer 106 may only be present above the device structure 104. In the case of a metallization layer, layer 106 may be patterned. Carrier 108 protects device structure 104 from damage and mechanically stabilizes semiconductor workpiece 100 during and / or after the cleaving process. In some examples, an additional layer 118 between layer 106 and carrier 108 may be foreseen.

[0042] The doped regions 110, 112, 114 of the device structure 104 are produced by implantation with a subsequent annealing step or by doping during the epitaxial process. For example, for a power MOSFET (metal oxide semiconductor field effect transistor) or power diode device, the first deposited epitaxial layer 114 can be an n-doped drain or emitter layer with a thickness ranging, for example, from 10 μm to 50 μm, or for an IGBT (insulated gate bipolar transistor) device, a p-doped emitter layer. A second epitaxially deposited layer (not shown) can be deposited as a buffer layer to prevent punch-through of the space charge layer toward the emitter / drain layer 114. The buffer layer typically has a thickness of 1 μm to 40 μm or 2 μm to 30 μm. The n-type drift zone layer 112 can then be deposited using epitaxial techniques. The thickness of the drift zone layer 112 depends on the target breakdown voltage (typically in the range of between 8 μm and 12 μm for 1200 V devices and between 25 μm and 35 μm for 3.3 kV devices). The doping level of the drift zone layer 112 can also be adjusted according to the desired breakdown voltage (typically around 1016 cm-3 for 1200 V devices and several times around 1015 cm-3 for 3.3 kV devices). The front-side device structures 110, such as the p-body and source regions for a power MOSFET or IGBT or the p-emitter for a power diode, can be formed by masked ion implantation with a subsequent annealing step. For switchable devices, the gate structure is also implemented in the form of a planar or trench-based gate.

[0043] After device formation, semiconductor workpiece 100 has a front side with a device structure 104 and a front side metallization layer and / or passivation layer 106. Device structure 104 can be a semiconductor device structure, such as a MEMS (micro-electromechanical system) and / or MOEMS (micro-opto-electromechanical system) device, a diode such as an MPS (merged pin Schottky) diode, a Schottky diode, a MOS gated diode, or a transistor device such as a MOSFET, a JFET (junction FET), an IGBT, a FinFET, a thyristor, or a combination thereof. If device structure 104 includes a Schottky contact, front side metallization layer 108 can include a Schottky contact metal. Additionally, or alternatively, in the absence of a Schottky contact, front side metallization layer 108 can include an ohmic contact metal.

[0044] In another embodiment, the semiconductor workpiece 100 may not be processed according to the above disclosure prior to cleaving, and the processing may begin with forming the separation region 116, as described below in conjunction with Figures 1B to 1E In this case, before the splitting begins, the semiconductor workpiece 100 does not include one or more epitaxial layers 102, device structures 104, layers 106, carriers 108, doped regions 110, 112, 114, and additional layers 118. In other words, in this embodiment, the original semiconductor workpiece can be split into two semiconductor crystals. The same applies to splitting semiconductor wafers from a crystal blank, where the crystal blank can be separated according to the embodiment of the present invention. Figure 1A In this case, the splitting process can be directly Figure 1B Start as described below.

[0045] Figure 1B The semiconductor workpiece 100 is shown after a separation region 116 is formed within the semiconductor workpiece 100. The separation region 116 has at least one altered physical property that increases thermomechanical stress within the separation region 116 relative to the remainder of the semiconductor workpiece 100. The separation region 116 allows the semiconductor workpiece 100 to be split at a defined location. The separation region 116 can extend along the horizontal direction of the wafer. Otherwise, splitting would occur at random locations that could be affected by crystal damage, etc. The well-defined separation region 116 can reduce material loss (also known as kerf loss) during wafer splitting. The thickness (t_sep) of the separation region 116 can define the kerf loss. For example, the loss can result from the vertical extent of microcracks and additional losses due to chemical, mechanical, electrochemical and / or plasma material removal.

[0046] In the case of processing the front side of a semiconductor workpiece, e.g. Figure 1AAs shown in , the position of the separation region 116 can be chosen such that after the device structure 104 is defined, the distance "d1" to the front side of the semiconductor workpiece 100 having one or more epitaxial layers 102 is high enough to allow mechanical handling of the thinner device wafer resulting from the cleaving process, and such that the distance d1 to the front side is low enough and therefore the distance "d2" to the back side is high enough so that the recycled wafer resulting from the cleaving process can still be handled. Figure 1A In the case of processing a semiconductor workpiece 100, the separation region 116 is close to the interface between the wafer 100 and the first deposited epitaxial layer 114 (the substrate / drain layer of a power MOSFET or the substrate / emitter layer of a diode). Typically, the separation region 116 is less than 10 μm, or even less than 4 μm, or even less than 2 μm from the interface between the wafer 100 and the first deposited epitaxial layer 114. Figure 1A In the case of processing, the distances "d1" and "d2" can be selected as needed, for example, "d1" and "d2" are equal. In particular, the distances "d1" and "d2" can define the thickness of the two semiconductor wafers after splitting. In the case of splitting the semiconductor wafer from the ingot, the distance "d1" can be selected to be substantially the thickness of the semiconductor wafer to be split from the ingot (taking into account the losses that occur during the splitting). The thickness of the semiconductor wafer can vary depending on the situation and can depend on the future use of the semiconductor wafer (typical thicknesses are, for example, 100 μm to 500 μm or 50 μm to 600 μm).

[0047] In general, thermomechanical stress may be increased within the separation region 116 compared to the remainder of the semiconductor workpiece 100 , thereby simplifying the splitting of the semiconductor workpiece 110 into device wafers and recycling wafers, for example, by applying mechanical forces.

[0048] In one embodiment, separation region 116 is formed by damaging material of semiconductor workpiece 100 at a target location. For example, in the case of SiC as the wafer material, the SiC material can be damaged. In some cases, the SiC can be at least partially decomposed into, for example, Si and C. This can be accomplished, for example, by generating a plasma in the SiC material at the target location within semiconductor workpiece 100. At least some atoms in the plasma can reform into carbon clusters and silicon material, for example, in the form of amorphous carbon and / or amorphous silicon. Additionally or alternatively, at least some atoms can recrystallize, semi-crystallize, and / or reform into, for example, at least one polytype of SiC (e.g., 4H-SiC, 6H-SiC, or 3C-SiC) or amorphous SiC, in which both Si and C phases are amorphous. In some examples, separation region 106 can include at least one of the following: a crystalline portion (e.g., in the form of microcrystals) of at least one polytype of SiC, silicon, or carbon, an amorphous portion of SiC, silicon, or carbon, and / or a cavity.

[0049] In one embodiment, a plasma is generated in the material at the target location within the semiconductor workpiece 100 by focusing laser radiation at the target location within the semiconductor workpiece 100. The semiconductor workpiece 100 can be irradiated through the back side opposite the device structure 104, or through the front side with (or without) the device structure 104 and focused to a well-defined area within the wafer 100 to ignite a plasma within the wafer 100, and the plasma decomposes the laser irradiated semiconductor material into its constituent components. For example, in the case of SiC, the laser irradiated SiC decomposes as follows: SiC → Si + C. The interaction with the laser radiation can result in different material phases, for example, as described above, and / or result in microscopic cracks within the semiconductor workpiece 100. In cases where the device structure 104 already exists (such as when the process is in progress), the plasma can be generated by focusing the laser radiation at the target location within the semiconductor workpiece 100. Figure 1A Initially), irradiating the semiconductor workpiece 100 with laser radiation through the front side may be done before producing the front side metallization 106, since the metallization 106 may not be transparent to the laser radiation.

[0050] If the separation zone 116 has been predefined, for example, by implantation as briefly explained above and explained in more detail below, the laser radiation applied to the separation zone 116 can be in a resonant regime in which single-photon processes (e.g., single-photon absorption) predominate, i.e., the probability of multi-photon processes is low (e.g., at least ten times lower than the probability of single-photon processes). In the resonant regime, the band gap of the material within the separation zone 116 can, for example, be within the range of the photon energy of the laser radiation (e.g., detuned from the band gap by at most ±5%, or at most ±1%, or at most ±0.1%, or at most ±0.01%, depending on the laser energy). The laser radiation can be absorbed in the separation zone 116 and can lead to further damage to the separation zone 116 (e.g., decomposition of the SiC in the case of the SiC wafer 100), so that no or only small mechanical forces are required to split the semiconductor workpiece 100 at the separation zone 116.

[0051] The separation zone 116 can be defined, or further defined, by focusing the laser radiation on a well-defined region, such as a region of the separation zone 116 within the semiconductor workpiece 100 having a thickness of at most a target, for example, at most 50% of the target thickness, in the case of a predefined layer previously formed, for example, by ion implantation. In this case, the laser radiation can be in a non-resonant state, so that the probability of single-photon processes in the separation zone 116 is low, and it may be necessary to account for a large proportion of multi-photon processes (particularly multi-photon absorption). For example, a non-resonant state can be achieved if the band gap of the separation zone 116 is larger than the photon energy of the laser radiation (for example, at least two times or at least ten times). In the case of multi-photon processes, the generation of damage can be further supported by a pre-defined layer (for example, formed by ion implantation) that increases absorption in the region where the focus of the laser radiation is located.

[0052] The laser radiation may be pulsed laser radiation. Parameters of the laser radiation (such as pulse duration, repetition rate, pulse energy, intensity, wavelength, pulse shape, polarization, etc.) are interconnected and can be optimized according to specific applications or requirements. For example, the laser radiation may have a pulse duration of 100 fs to 100 ns (e.g., 50 ps to 10 ns), a repetition rate of 10 kHz to 10 MHz, a pulse energy of 100 nJ to 50 μJ, and a peak wavelength of 400 nm to 2100 nm (e.g., 900 nm to 1200 nm).

[0053] The laser radiation can be applied along laser lines (also referred to as scribe lines) running substantially parallel to one another. For each laser line, the laser beam is scanned along the line. The speed of the laser scanning can be so fast that adjacent individual laser shots can be distinguished, e.g., without overlapping. Here, an individual laser shot may correspond to damage produced by a single laser radiation pulse, e.g., Figure 2 As shown in .

[0054] In the diagram showing a small portion of the separation zone 116 Figure 2 , the dotted ellipses marked "A" correspond to the locations of separate / single laser shots. At each single laser shot location "A," the material of the separation region 116 is decomposed, and microcracks extending along the crystal planes of the wafer material appear, as indicated by the additional microcracks marked "B" and "C." The microcracks "A," "B," and "C" formed within the separation region 116 are at least partially disconnected from one another. The microcrack marked "C" is generated by tension between the other microcracks "A" and is not directly formed by the laser shot. For 4H-SiC, the growth direction of the semiconductor workpiece 100 (which corresponds to the vertical direction along which the wafer 100 has a thickness T_wafer) can be slightly tilted toward the main crystal axis, typically by 4° (also referred to as the off-axis angle). As a result, the crystal planes are tilted.

[0055] If separation zone 116 were to have only a single large crack, which would be planar but tilted, separation zone 116 would be tilted 4° relative to the lateral direction (i.e., the direction perpendicular to the vertical direction). This would result in considerable losses along the entire diameter of semiconductor workpiece 100. Therefore, as with SiC, the cleavage process may be useful for 4H-SiC if the cleavage plane is not planar but has a zigzag / sawtooth shape. Microcracks "A," "B," and "C" are then connected to enable cleavage of semiconductor workpiece 100, as described in more detail further below.

[0056] In addition to or as an alternative to damaging the semiconductor workpiece 100 by laser irradiation to form the separation region 116, the material of the semiconductor workpiece 100 can be damaged at a target location by implanting ions into the semiconductor workpiece 100 at a depth corresponding to the target location within the wafer 100 to create and / or predefine the separation region 116. The ions can directly lead to higher absorption, for example, due to a higher absorptivity in the separation region 116 where the majority of the implanted ions reside. In the case of SiC as the material of the semiconductor workpiece 100, the ions can cause the crystal structure of the SiC wafer to transform into a different material, for example, into a different polycrystalline type (e.g., from 4H-SiC to 3C-SiC) and / or into a different degree of crystallinity and / or into amorphous SiC and / or into silicon and carbon (amorphous or crystalline), resulting in an increased absorption coefficient at the wavelength of the laser irradiation in the separation region 116. The ions can also cause the material of the semiconductor workpiece 100 to decompose in the separation region 116.

[0057] In one embodiment, the ions may be selected from the group consisting of nitrogen ions, phosphorus ions, hydrogen ions, and helium ions. For example, atoms such as nitrogen and / or phosphorus atoms may be implanted into the separation region 116 at an implantation dose that results in the creation of an amorphous layer and / or a cavity. Additionally or alternatively, helium ions or protons may be implanted to create a localized damage layer within the separation region 116. For the same energy, light ions such as helium and hydrogen penetrate deeper into the semiconductor workpiece 100 than heavier ions, thereby increasing the depth of the separation region 116 (if desired). Light ions such as helium and hydrogen may preferentially create vacancy clusters and a damage layer at the extreme ends of the implantation range, thereby promoting the splitting process in this region. Phosphorus and / or nitrogen are suitable for achieving highly damaged layers in SiC. In the case of phosphorus and / or nitrogen, the implantation dose may be selected to create an amorphous layer and / or a cavity in the separation region 116. Optionally, channeling may be utilized during implantation, resulting in reduced surface damage to the surface into which the implantation is performed. The ions may be implanted prior to forming one or more epitaxial layers 102. For example, ions may be implanted through a surface of the semiconductor workpiece 100 where one or more epitaxial layers 102 are to be formed.

[0058] In cases where the device structure is produced before splitting (e.g., according to Figure 1AGiven the disclosure provided herein, device structure 104 can be created after ion implantation. After or before creating device structure 104, laser radiation, as described above, can be irradiated through semiconductor workpiece 100, with the focus positioned approximately at the implanted layer. The ions and / or the semiconductor material that has been converted by the ions will have increased absorption compared to the remainder of wafer 100, thereby improving, for example, the decomposition of SiC into Si and C through enhanced local heating of wafer 100. For example, a combination of multi-photon and single-photon processes can occur within the predefined ion implanted layer to increase the thermomechanical stress within separation region 116 relative to the remainder of semiconductor workpiece 100.

[0059] In one embodiment, the separation region 116 is formed by both laser irradiation and ion implantation of the semiconductor workpiece 100. In particular, by implanting ions into the semiconductor workpiece 100 at a depth corresponding to a target location within the wafer 100, the material of the semiconductor workpiece 100 can be damaged at the target location within the semiconductor workpiece 100. After the ion implantation, the laser radiation is then focused at the target location within the semiconductor workpiece 100. According to this embodiment, the implanted ions increase the absorption coefficient in the separation region 116 at the wavelength of the laser radiation, which further increases the thermomechanical stress within the separation region 116 relative to the rest of the semiconductor workpiece 100.

[0060] After separation zone 116 is formed, an external force is applied to semiconductor workpiece 100, causing at least one large crack to propagate along separation zone 116 and splitting semiconductor workpiece 100 into two separate wafers. The force balance of surface energy, bonding forces, and (optionally) external pressure shifts in favor of the external force, overcoming any remaining internal bonding forces within semiconductor workpiece 100 at separation zone 116, thereby causing crack propagation. Alternatively, laser radiation may propagate a sufficient crack along separation zone 116 that the application of external force is not necessarily required to split semiconductor workpiece 100. However, external force may still be applied to assist in the lift-off process of the split wafer wafers and / or wafer splitting.

[0061] As explained above, the separation region 116 has at least one altered physical property that increases the thermomechanical stress within the separation region 116 relative to the remainder of the semiconductor workpiece 100. For example, laser irradiation and / or ion implantation can be used to alter at least one physical property of the separation region 116. The laser irradiation can form microscopic cracks "A," "B," and "C" in the separation region 116, while the implanted ions can increase the absorption coefficient in the separation region 116 at the wavelength of the laser irradiation. The local increase in thermomechanical stress limits the propagation of cracks into the separation region 116 in a controlled and reproducible manner.

[0062] Figures 1C to 1EAn embodiment is shown in which an external force is applied to the semiconductor workpiece 100 for splitting the wafer 100 along the separation zone 116. According to this embodiment, the polymer 120 is applied to the semiconductor workpiece 100 (such as from below, as shown in FIG. Figure 1C ). Figure 1C As shown in FIG, the polymer may also optionally be applied to the carrier 108 (such as from above, as shown in FIG. Figure 1C (as indicated in the ).

[0063] Figure 1C The device structure (such as epitaxial layer 102, device structure 104, layer 106, carrier 108, doped regions 110, 112, 114, and additional layer 118) is shown. As discussed, the device structure is optional and need not be present. The polymer 120 has a CTE (coefficient of thermal expansion) that is different from the CTE of the semiconductor workpiece 100. The polymer 120 and the semiconductor workpiece 100 are then subjected to a temperature process during which the polymer 120 applies mechanical stress to the semiconductor workpiece 100, such as Figure 1D The mechanical stress causes at least one large crack 122 to propagate along the separation region 116, so that the semiconductor workpiece 100 is split into two separate crystal pieces 124 and 126. Figure 1E . One wafer 124 retains the device structure 104 (if present) or can be used for subsequent processing (if the device structure is not present). The other wafer 126 can be used for subsequent device processing. In the case where the semiconductor wafer is split from the ingot, polymer 120 can be applied to the surface of the ingot closer to the separation region 116.

[0064] The separation zone 116 includes the above combination Figure 2In the case of the microcracks "A," "B," and "C" explained above, the mechanical stress applied to the semiconductor workpiece 100 causes the microcracks "A," "B," and "C" to connect with one another to form a macrocrack 122 in the split wafer 100. That is, the individual microcracks "A," "B," and "C" are displaced relative to one another in response to the external force. Therefore, the separation region 116 cannot be considered a single layer within the semiconductor workpiece 100, but rather a combination of several microcracks "A," "B," and "C" that combined during the splitting process. In the case of SiC as the material of the semiconductor workpiece 100, the combined microcracks "A," "B," and "C" result in the two separated wafers 124 and 126 having separation surfaces 128 and 130 with a sawtooth pattern. Therefore, in the case of SiC, the resulting device wafer 124 and recycled wafer 126 do not have smooth, flat surfaces. In one embodiment, after the semiconductor workpiece 100 is split into two separate dies 124, 126, each separation surface 128, 130 generated by the macrocrack 122 propagating along the separation region 116 is smoothed. Residual decomposed material may be present at the separation surface 128, 130 of each die 124, 126 split from the wafer 100 and may be removed by a cleaning process.

[0065] The polymer 120 can be attached to the semiconductor workpiece 100, wherein the carrier 108 is already attached to the wafer 100 (if a device structure is present). The polymer 120 can be attached to the semiconductor workpiece 100 at a side facing away from the front and the back side 132 of the carrier 108. The polymer 120 can also be attached to an outer side 134 of the carrier 108 facing away from the semiconductor workpiece 100 (if present). In the absence of the device structure 104, the polymer can be attached to the front side of the semiconductor workpiece 100 ( Figure 1C In general, additional layers (e.g., bonding layers such as adhesives, and / or layers that simplify later removal of polymer 120) may be applied between polymer 120 and the side to which polymer 120 is applied. Polymer 120 may also be applied only to backside 132 of semiconductor workpiece 100 or only to the front side of wafer 100.

[0066] The polymer 120 can be selected not only based on CTE, but also by considering multiple parameters. The CTE of the polymer 120 should be different from the CTE of the semiconductor workpiece 100. For example, the CTE of the polymer 120 is preferably greater than the CTE of the semiconductor workpiece 100. In addition to the CTE difference, a linear CTE profile in the polymer 120 over a wide temperature range may be advantageous for successful separation.

[0067] Furthermore, polymer 120 should have sufficiently high thermal conductivity. In one embodiment, one or more fillers, such as ZnO and / or carbon black, are added to polymer 120 prior to the temperature process. The filler(s) can increase the thermal conductivity of polymer 120 and can reduce the slope of the storage modulus of polymer 120, thereby extending the linear course of the CTE in polymer 120 over a narrower temperature range. By adding ZnO and / or carbon black to polymer 120, the percolation chains formed can increase the thermal conductivity of polymer 120. If a filler material is used, the polymer material can be selected so that the filler material is evenly distributed throughout polymer 120. An example of polymer 120 is PDMS (polydimethylsiloxane), which typically has at least one filler. PDMS can exhibit high adhesion to surfaces. Therefore, attachment may require some pretreatment or conditioning to allow for non-destructive removal of the polymer. For example, a foil can be positioned between the polymer and the surface to which it is attached.

[0068] Attaching polymer 120 is typically performed at elevated temperatures (e.g., above room temperature but below 300° C.). A bonding process can be employed to allow for a secure bond throughout the entire temperature process. For example, prior to applying polymer 120, the application surfaces of polymer 120 and / or semiconductor workpiece 100 and / or carrier 108 can undergo chemical and / or physical surface treatment (e.g., with plasma) to allow for secure bonding. An indirect temporary cold plasma activation process can be used to ensure easy subsequent removal of polymer 120.

[0069] Another additional or alternative approach is to apply a bonding (sacrificial) layer between the semiconductor workpiece 100 and the polymer 120. The bonding layer can be selected so that adhesion to the polymer 120 can be reduced, for example, using chemicals or heat treatment. The polymer 120 may not be produced directly on the semiconductor workpiece 100 and / or directly on the carrier 108. Instead, the polymer 120 may be produced in advance and subsequently attached to the semiconductor workpiece 100 and / or the carrier 108.

[0070] After polymer 120 is attached to semiconductor workpiece 100 (and / or carrier 108, if applicable), a temperature process is performed. In one embodiment, the temperature process is selected so that polymer 120 undergoes a partial glass transition and partial crystallization during the temperature process. This process may include a first phase, during which polymer 120 and semiconductor workpiece 100 undergo a temperature gradient from a starting temperature of 300°C or less but above room temperature to room temperature, and a second phase, during which polymer 120 and semiconductor workpiece 100 are further cooled to a lower temperature. For example, the lower temperature may correspond to ±40°C of the boiling temperature of the cooling liquid (e.g., liquid nitrogen) used for cooling. The lower temperature may be, for example, -170°C, particularly for the entire wafer 100. In some examples, depending on the cooling conditions (e.g., the cooling liquid), the lower temperature may be below the glass transition temperature (Tg) of polymer 120.

[0071] Figure 3A and Figure 3B The same polymer 120 is shown without filler ( Figure 3A ) and one or more fillers ( Figure 3B ), the storage modulus (elastic modulus) in MPa within the temperature in ° C. During the second stage of the temperature process, the polymer 120 may undergo a partial glass transition and a partial crystallization process, such as Figure 3A and Figure 3B The definition of the glass transition Tg has not yet been standardized. There are several methods for determining Tg, which is not a constant material property but depends on the method used to define Tg and also on the parameters used during the method. For example, if the DMA (Dynamic Mechanical Analysis) method for measuring the viscoelastic modulus is used, the dynamic glass transition temperature and also the parameters used for the measurement (e.g. frequency of the external load, ramping speed, ramping direction, measurement accuracy, etc.) must be stated. Figure 3A In the glass transition temperature, Tg, occurs at the inflection point (at least for some methods of defining Tg). Figure 3B The temperature at which crystallization begins (slower slope between T1 and T2) is higher than the temperature of the glass transition (higher slope below T2), where T3 is lower than T2, and T2 is lower than T1. Figure 3A By adding one or more fillers to polymer 120, the polymer used has the freedom to crystallize earlier than the polymer without filler.

[0072] During the wafer splitting process, pressure may be applied to the semiconductor workpiece 100. For example, a piston may apply pressure to the semiconductor workpiece 100 having one or more epitaxial layers 102. The piston may be pushed toward the wafer 100 using compressed air, or simply the weight of the piston may be applied to the wafer 100.

[0073] After the semiconductor workpiece 100 is split, the wafer 124 retaining the device structure 104 can be thinner than the other wafer 126. For example, the wafer 124 retaining the device structure 104 can have a thickness of at most 100 μm (e.g., at most 70 μm or at most 50 μm) and at least the required thickness of the drift zone as described above (or at least 10 μm greater than the required thickness), and the other wafer 126 can have a thickness of at least 150 μm (e.g., at least 190 μm). In the case where the semiconductor wafer is split from the ingot, the thickness of the semiconductor wafer can be at least 150 μm (e.g., at least 190 μm) or thicker, depending on the purpose of the semiconductor wafer's subsequent use.

[0074] Thereafter, the polymer 120 on both the device-side separation surface 128 (if applicable) and the recovery-side separation surface 130 may be removed by mechanical means.

[0075] After wafer splitting, the split wafer crystals 124, 126 are processed on the separation surfaces 128, 130 of the crystals 124, 126 (or the separation surfaces of the split wafer crystals and the rest of the crystal blank). For the back side of the crystal 124 with the device structure 104, damage removal can be performed, for example by mechanical grinding and / or chemical mechanical polishing and / or etching. The final roughness of the separation surface 128 after damage removal can have a root mean square (rms) value of less than 5 μm or even less than 2 μm. Further processing can then follow. In the case of the crystal 126 without the device structure 104, the separation surface 130 may need to be processed to prepare for subsequent epitaxial growth. In this case, the rms value of the separation surface 130 can be less than 500 nm or even less than 300 nm. The thickness of wafer 126 without device structure 104 may be adapted to the original thickness of wafer 100 , for example by means of deposition techniques such as CVD-epitaxial techniques, so that the same process as described above may be repeated several times for thickened wafer 126 .

[0076] The wafer splitting as described above can also be performed with the arrangement turned upside down. Figure 1D and Figure 1E In the wafer splitting shown in , a recovery wafer (corresponding to the remaining portion of the ingot in the case where the semiconductor wafer is split from the ingot) may be located on top of the semiconductor wafer corresponding to wafer 124 .

[0077] According to the present disclosure, a semiconductor workpiece (e.g., a semiconductor ingot or a semiconductor wafer, both of which are made of Figures 1A to 1E The ingot (or semiconductor wafer) 100 (indicated by reference numeral 100 in the figure) can be placed on an apparatus configured to hold a polymer 120. In this context, "placed on" can mean that the semiconductor workpiece is positioned above the apparatus and that the semiconductor workpiece is in contact (e.g., direct contact) with the apparatus (particularly the polymer), or "placed on" can mean that the apparatus is positioned above the semiconductor workpiece and that the apparatus (particularly the polymer) is in contact (e.g., direct contact) with the semiconductor workpiece. The apparatus can include a frame surrounding the polymer, which is connected to the polymer. For example, after the separation region 160 is formed and before the temperature process begins, the ingot (or semiconductor wafer) 100 can be attached to the polymer. The frame can be in the form of a wafer ring, which is typically used for processing semiconductor wafers, such as for dicing semiconductor wafers. For example, the wafer ring can be a metal frame. This allows the apparatus (with or without the ingot attached thereto) to be handled by typical semiconductor manufacturing equipment configured to handle typical semiconductor frames. The ingot can then be attached to the polymer, for example, by the side from which the semiconductor wafer will be cleaved. The apparatus, together with the ingot attached thereto, may then be subjected to a heat treatment in order to split the semiconductor wafers from the ingot (as described above).

[0078] Figure 4A and Figure 4B An exemplary apparatus 10 is illustrated that can be used to hold a workpiece during a cleaving process. In this example, the workpiece is a crystal blank 100. In other examples, the workpiece can be a semiconductor wafer. For example, the apparatus can be used to attach a polymer to the crystal blank 100. In particular, Figure 4A A side view of the device 10 is shown, and Figure 4B The diagram illustrates a top view of device 10. Device 10 may include polymer 20 and frame 30. Polymer 20 may have the same properties as (or be the same polymer as) polymer 120 discussed above with respect to Figures 1 to 3. Furthermore, device 10 may include a foil 40 fixedly attached (such as laminated) to frame 30. Polymer 20 may be disposed on foil 40, thereby providing a connection between frame 30 and polymer 20. Frame 30 is connected to and surrounds polymers 20, 120. In one example, foil 40 is a dicing foil typically used when dicing semiconductor wafers.

[0079] Frame 30 may have an inner diameter 30d, an outer diameter 30d, and a width 30w. The width may be at least 10 mm, or at least 20 mm. The width may be at most 100 mm, or at most 80 mm, or at most 50 mm. Outer diameter 30d may be at least 20 cm, or at least 26 cm, or at least 28 cm. Outer diameter 30d may be at most 40 cm, or at most 35 cm, or at most 31 cm. The inner diameter may be at least 18 cm, or at least 20 cm, or at least 25 cm. The inner diameter may be at most 35 cm, or at most 30 cm, or at most 29 cm.

[0080] The apparatus 10 can allow for efficient handling of the polymers 20, 120, eliminating the need to manually place the polymers 20, 120 on the ingot 100. In one example, the frame 30 can be a wafer ring (e.g., a so-called dicing ring or dicing frame), which is typically used (e.g., in conjunction with a dicing foil) to process wafers in typical semiconductor manufacturing machines. This can allow the same semiconductor manufacturing machine to be used to handle the ingot 100 placed on the foil 40 connected to the wafer ring. The polymers 20, 120 can be fixedly attached to the foil 40. This can be achieved through the adhesion of the polymers 20, 120 themselves or through an additional adhesion step, such as laminating the polymers 20, 120 to the foil 40.

[0081] Figure 4B The frame 30 is depicted as a perfect ring having inner and outer circles and a constant width along the circumference of the frame 30. However, the shape of the frame 30 may deviate from the perfect ring. Figure 4C Examples of irregular shapes for frame 30 are depicted in FIG. The outer edge of frame 30 may include regions 301, 302 that deviate from a circular or elliptical shape. The widths 30w1, 30w2 of frame 30 along the circumference may vary. For example, frame 30 may include regions having a larger first width 30w1 than regions having a narrower second width 30w2. Frame 30 may include a flat region 301 (i.e., where the outer edge follows a straight line). Flat region 301 may abut circular region 302. The first outer diameter 30D2 of frame 30 in flat region 301 may be smaller than the second outer diameter 30D1 of frame 30 in circular region 302. Frame 30 may include additional regions 303, such as indentations. While the outer edge's contour generally still follows a circular shape, particularly the circular shape defined by circular region 302, the inner edge of frame 30 may similarly deviate from a circular or elliptical shape in various regions, though generally the shape of the inner edge is closer to a ring. Figure 4CThe frame 30 depicted in FIG may be a so-called cutting frame. The frame 30 may be a so-called 8-inch cutting frame. This may allow for easier handling with standardized manufacturing equipment. The 8-inch cutting frame may be used for ingots or wafers having diameters of 150 mm and 200 mm. The first outer diameter 30D1 may be 296±1 mm, and the second outer diameter 30D2 may be 276±1 mm. The inner diameter 30d of the frame 30 may be 250±1 mm (for a standard 8-inch cutting frame). In other examples, the inner diameter 30d of the frame 30 may be at least the outer diameter of the polymer, for example, at least 160 mm for a 150 mm ingot or wafer, or at least 210 mm for a 200 mm ingot or wafer. In this case, the first outer diameter 30D1 and the second outer diameter 30D2 may still be the same as a standard 8-inch cutting frame, allowing for easier handling with standardized manufacturing equipment.

[0082] As discussed above, the polymer 20, 120 can undergo a partial glass transition when cooled below a critical temperature, and can be elastic when having a temperature above the critical temperature. The polymer 20, 120 includes a first region 21A having a surface 22A to which the blank 100 can be attached. In some examples, the first region is equal to the entire polymer 20, 120. In other examples, the polymer can include additional regions that are not attached to the semiconductor workpiece. For example, the polymer 20, 120 can have a diameter of about 15 cm or about 20 cm. When the blank 100 is attached to the surface 22A of the polymer 20, 120 of the device 10, cooling the polymer 20, 120 below the critical temperature can apply a force to the blank 100, which causes the blank 100 to split (as discussed above with respect to FIG. Figures 1B to 1E As described above, for example, first region 21A of polymer 20, 120 may shrink due to a partial glass transition. This force (which may arise from this shrinkage) may be applied not only to ingot 100 but also to foil 40. This force may cause foil 40 to pull frame 30 toward polymer 20, 120 located at the center of frame 30 (due to foil 40 being fixedly attached to polymer 20, 120 and frame 30). In some cases, this may cause the frame to deform, potentially damaging it after cooling.

[0083] Figures 5A to 5C Another exemplary apparatus 10 is illustrated that may be used to hold a blank 100 during the splitting process. In particular, Figure 5A and Figure 5B Each illustrates a side view of an embodiment of apparatus 10, and Figure 5CFIG shows an exemplary top view of device 10. Device 10 may include frame 30 and polymer 20. Frame 30 may have Figure 5C or it may deviate from the ideal circular shape, for example as shown in conjunction with Figure 4C 1-4 . Polymer 20 can have the same properties as (or be the same polymer as) polymer 120 discussed above with respect to FIGS. 1-4 . Polymer 20, 120 can have a surface 22A of a first region 21A to which ingot 100 can be attached, and which will be cooled below the critical temperature of polymer 20, 120 in order to undergo a partial glass transition to split ingot 100 (as discussed above). Optionally, polymer 20, 120 can additionally have a second region 21B that will not undergo a transition during cooling (e.g., by not cooling second region 21B below the critical temperature). As such, while first region 21A of polymer 20, 120 undergoes a transition and contracts (due to being cooled below the critical temperature), second region 21B can maintain its elastic properties. This can allow second region 21B of polymer 20, 120 to relieve forces applied to frame 30, so that frame 30 may not be deformed by the forces applied by first region 21A of polymer during the transition. Surface 22A of the first region has a substantially circular shape with a diameter of approximately 15 cm or 20 cm (depending on the size of the workpiece). For example, the diameter of surface 22A can correspond to the diameter of semiconductor workpiece 100 to which polymer 20, 120 can be attached (with a deviation of at most ±20%, at most ±10%, or at most ±5%). The diameter of surface 22A can, for example, correspond to at least 105% or at least 110% of the diameter of the semiconductor workpiece.

[0084] Second zone 21B may not overlap with first zone 21A of polymer 20, 120 and may surround first zone 21A of the polymer. The surface of second zone 21B may have a substantially annular shape, wherein the inner circle of the ring is substantially defined by surface 22A of first zone 21A, and wherein the outer circle of the ring has a diameter of at least 18 cm, at least 20 cm, at least 25 cm, or at least 30 cm. This ensures that second zone 21B does not undergo a partial glass transition (or at least a portion of second zone 21B does not undergo a partial glass transition) when first zone 21A is cooled below the critical temperature. In particular, by substantially cooling only first zone 21A of polymer 20, 120 and not cooling second zone 21B of polymer 20, 120, a temperature gradient can be established within polymer 20, 120, the temperature of which is above the critical temperature in at least a portion of second zone 21B. Then, while first region 21A of polymer 20, 120 undergoes a partial glass transition, portions of second region 21B of the polymer can remain elastic and mitigate the force applied by first region 21A of polymer 20, 120. This can mitigate the force applied to the frame, potentially preventing (or at least minimizing) damage to frame 30. It is possible that the thickness of polymer 20, 120, perpendicular to surface 22A, is greater in first region 21A than in second region 21B. In this case, a transition region where the thickness decreases can exist between first region 21A and second region 21B. Alternatively or in combination, the surface roughness of at least one surface of the polymer can be greater in first region 21A than in second region 21B. The reduced thickness and / or higher surface roughness in the second region can reduce the manufacturing cost of the polymer.

[0085] like Figure 5A As shown in FIG, polymer 20, 120 can be directly attached to frame 30, for example, via attachment elements 31 protruding from frame 30 (such as hooks or holes in the frame material). For example, attachment elements 31 can protrude toward polymer 20, 120. Attachment elements 31 can be part of frame 30 or fixedly connected to the frame. Polymer 20, 120 can be molded (e.g., injection molded) onto attachment elements 31 to form a secure connection between polymer 20, 120 and frame 30. For example, a portion of polymer 20, 120 can be molded around attachment elements 31. The distance from attachment element 31 (e.g., the center of attachment element 31) to the upper surface of frame 30 can differ from the distance from attachment element 31 (e.g., the center of attachment element 31) to the opposing lower surface of frame 30 by at most + / - 20%, for example, at most + / - 10%. Attachment elements 31 can be positioned symmetrically relative to the upper and lower surfaces of frame 30.

[0086] Alternatively, the polymer 20, 120 may have attachment elements 23, such as protrusions and / or fingers and / or hooks, which may be disposed in the voids of the frame 30 (e.g., via molding) to form a secure connection between the polymer 20, 120 and the frame 30 (e.g., Figure 5B ). For example, polymers 20, 120 can be molded into the voids of the frame. The voids can be symmetrically positioned relative to the upper and lower surfaces of the frame 30. For example, the distance from the center of the void to the upper surface of the frame 30 can differ from the distance from the center of the void to the opposite lower surface of the frame 30 by at most + / - 20%, such as at most + / - 10%.

[0087] First region 21A of polymer 20, 120A and second region 21B of polymer 20, 120 can be formed from the same piece of polymer 20, 120. First region 21A and second region 21B can have the same thickness, or the thickness of second region 21B can be less than the thickness of first region 21A. The entire polymer 20, 120 can have a diameter that is at least 120% of the diameter of the semiconductor workpiece (e.g., at least 20 cm for a semiconductor workpiece having a diameter of 150 mm, such as ingot 100 or wafer).

[0088] The (optional) second region 21B can essentially form a ring having an inner diameter that is at most 120% or equal to the diameter of the semiconductor workpiece 100 attached to the first surface 21A, and an outer diameter that is at least approximately 120% of the diameter of the semiconductor workpiece 100 (e.g., an inner diameter of 150 mm, 160 mm, or 170 mm, and an outer diameter of 18 cm). In the case of an outer diameter of 18 cm, when a semiconductor workpiece 100 having a diameter of 150 mm (such as a 6-inch SiC ingot) is attached to the first surface 21A, the ring can have a width of at most 1.5 cm. This can ensure that when the first region 21A is cooled below the critical temperature, at least a portion of the second region 21B can avoid undergoing a partial glass transition and can remain resilient to mitigate forces (as discussed above). In other examples, the outer diameter of second region 210B can be at least 20 cm, or at least 25 cm, or at least 30 cm, or at least 40 cm, or at least 50 cm, or at least 60 cm, or at least 70 cm, or at least 80 cm, or at least 100 cm. As a general rule, the larger the diameter of semiconductor workpiece 100, the larger the outer diameter of polymer 20, 120 should be selected. In some examples, a thermal insulator can be provided between first region 21A and second region 21B of polymer 20, 120. In some examples, polymer 20, 120 can be formed from a single part.

[0089] Figure 6Another embodiment of the present disclosure is shown. Specifically, the frame 30 can be an assembly of multiple components. Specifically, the frame 30 can include an outer ring 34 that is removably attached to a flexible ring. The flexible ring can include three or more ring elements 32 and corresponding three or more flexible attachment elements 33. Each flexible attachment element 33 can connect two corresponding ring elements 32 of the three or more ring elements to each other to form the flexible ring. Figure 6 An example is shown having six ring elements and corresponding six flexible attachment elements 33. Of course, other embodiments are possible, for example, having three ring elements 32 and corresponding three flexible attachment elements 33 (or four, five, seven, eight, nine, ten, etc.). As discussed above, the polymer 20, 120 can be connected to the frame 30 by directly attaching the polymer 20, 120 to the frame 30, for example, via attachment elements 31 (such as hooks or holes) protruding from the frame 30, as shown. Figure 5A , or by attachment elements 23, such as protrusions and / or fingers and / or hooks, which may be provided in the interstices of the frame (e.g. via molding) to form a secure connection between the polymer 20, 120 and the frame 30 (e.g. Figure 5B ). Figure 6 In the exemplary disclosure of the present invention, the attachment element 31 may protrude from the ring element 32 / a void may be formed in the ring element 32. In the case where the polymer is directly attached to the flexible ring of the frame 30, the flexible ring formed by the ring element 32 and the flexible attachment element 33 may have an inner diameter substantially equal to the outer diameter of the second region 21B of the polymer 20, 120. In another embodiment, the polymer 20, 120 may be attached to the frame 30 via a bonding Figure 4A and Figure 4B The disclosed foil 40 is connected to the flexible ring of the frame 30. As discussed above, the polymer can be attached to the foil 40 (e.g., by laminating the polymer 20, 120 to the foil), and the foil 40 can be attached to the flexible ring of the frame 30 (e.g., by lamination).

[0090] The flexible attachment element 33 can securely connect the ring elements 32 to each other. Furthermore, when no external force is applied to the flexible rings, the flexible attachment element 33 can allow the flexible rings to have a first inner diameter, and when an external force directed toward the center of the flexible rings is applied, the flexible attachment element 33 can allow the flexible rings to have a second inner diameter that is smaller than the first inner diameter. This can allow the flexible rings to mitigate the forces generated by the contraction of the polymers 20, 120 when the polymers undergo a partial glass transition. For example, the flexible attachment element 33 can include a spring or suspension assembly that can contract (e.g., shrink) under pressure. For example, when no external force is applied to the flexible rings, two adjacent ring elements 32 can have a gap between them. When an external force directed toward the center of the flexible rings is applied to the ring elements 32, the flexible attachment element can contract, causing the gap between the ring elements 32 to become smaller. This can allow the flexible ring to contract from a first diameter (when no external force is applied) to a smaller diameter (when a force directed toward the center of the flexible ring is applied to the ring element, e.g., from polymer 20, 120 contracting while undergoing a partial glass transition). When the external force reaches a threshold force, the gap can disappear or a minimum gap size can be reached. For example, the ring elements 32 can include a void into which the flexible ring element can slide when an external force is applied. Each ring element 32 can span an angle of the flexible ring. The ring elements 32 can all be the same size, or they can have different sizes, e.g., one ring element having a greater length than the others. When assembled with the flexible attachment element 33 (and when no external force is applied), the ring elements 32 can form a ring having an inner diameter, e.g., 18 cm, 20 cm, 25 cm, or greater (the inner diameter can depend on the diameter of the polymer 20, 120), and an outer diameter, e.g., 23 cm, 25 cm, or 30 cm (e.g., 5 cm greater than the inner diameter of the flexible ring). The flexible ring may be removably attached (such as mounted) to an outer ring 34 of the frame 30. The outer ring 34 may be a rigid frame that provides stability to the flexible ring.

[0091] Figure 7 The use of the apparatus 10 according to the present disclosure is illustrated in a process of splitting a semiconductor workpiece 100. After a separation region 116 has been formed within the ingot 100, the semiconductor workpiece 100 (such as an ingot or semiconductor wafer) can be attached to a surface 22A of a first region 21A of a polymer 20, 120. The semiconductor workpiece 100 can be attached to the apparatus 10 such that a surface of the ingot is positioned on the apparatus 10 at a closer distance to the separation region 116 within the semiconductor workpiece 100 than another surface of the semiconductor workpiece.

[0092] Figure 8 The method for splitting a semiconductor workpiece according to an embodiment of the present disclosure is illustrated. Figure 1AAs discussed, the method may optionally include forming one or more epitaxial layers on the semiconductor workpiece, forming a plurality of device structures in the one or more epitaxial layers, forming a metallization layer and / or a passivation layer above the plurality of device structures, and attaching a carrier with the one or more epitaxial layers on top of the device structures, the carrier protecting the plurality of device structures.

[0093] The method may then include step 810 of forming a separation region within the crystal blank or within the semiconductor wafer. The separation region may have at least one altered physical property that may increase thermomechanical stress within the separation region relative to the remainder of the semiconductor workpiece. In some examples, forming the separation region within the semiconductor workpiece includes damaging the material of the semiconductor workpiece at a target location within the semiconductor workpiece. In an embodiment, damaging the material of the semiconductor workpiece at a target location within the semiconductor workpiece may include generating a plasma in the material at the target location within the semiconductor workpiece. For example, generating the plasma in the material at the target location includes focusing laser radiation at the target location. Additionally or alternatively, damaging the material of the crystal blank or semiconductor wafer at the target location may include implanting ions into the semiconductor workpiece at a depth corresponding to the target location. The implantation dose of the ions may be selected such that the material of the semiconductor workpiece damaged by the implanted ions is amorphous or creates a cavity. For example, the ions are selected from the group consisting of nitrogen ions, phosphorus ions, hydrogen ions, and helium ions. In some embodiments, damaging the material of the ingot or semiconductor wafer at a target location may include implanting ions into the semiconductor workpiece at a depth corresponding to the target location; and after implanting the ions, focusing laser radiation at the target location, wherein the implanted ions increase the absorption coefficient in the separation region at the wavelength of the laser radiation.

[0094] The method can then proceed to step 820 of attaching a semiconductor workpiece to a first region of a polymer surface. The polymer is included in an apparatus for holding a semiconductor workpiece during cleavage. The apparatus includes a polymer and a frame, wherein the frame is connected to and surrounds the polymer, wherein the polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when at a temperature above the critical temperature, wherein the polymer includes the surface. The apparatus can be combined Figures 4A to 6The polymer may include a second region that does not overlap with a first region of the surface. The second region may surround the first region of the polymer and may be sized such that, during a subsequent cooling step (as described further below), at least a portion of the second region of the polymer remains above a critical temperature. This ensures that, during the glass transition of the first region of the polymer, while the first region of the polymer contracts, the second region of the polymer remains elastic and can be stretched. Accordingly, the diameter of the first region of the polymer may be substantially equal to the diameter of a semiconductor workpiece placed on the polymer (e.g., 15 cm, 20 cm, or 30 cm). The second region may have a substantially annular shape, with the inner circle of the ring being defined by the surface of the first region, and the outer circle having a diameter selected such that, when the semiconductor workpiece is cooled, at least a portion of the second region does not undergo a glass transition (e.g., an outer circle having a diameter of at least 18 cm, 20 cm, 25 cm, 30 cm, 40 cm, 50 cm, 60 cm, 700 cm, or greater). In some examples, the second region of the polymer may reach the frame of the device and may be directly connected to the frame. The semiconductor workpiece can be attached to the apparatus such that a surface of the ingot is positioned on the apparatus at a closer distance to a separation region within the semiconductor workpiece than another surface of the semiconductor workpiece. In some examples, the semiconductor workpiece may not be directly disposed on the polymer, and a bonding (sacrificial) layer may be disposed between semiconductor wafer 100 and polymer 120. 17. Furthermore, before the surface of the first polymer region is attached to the semiconductor workpiece, the surface of the first polymer region and / or the surface of the ingot (or semiconductor wafer) may be chemically and / or physically treated.

[0095] In a subsequent step, the method may include cooling 830 the ingot or semiconductor along with the first region of the device to a temperature below the critical temperature. This may be performed to apply external force to the semiconductor workpiece, causing at least one crack to propagate along the separation region and split the semiconductor workpiece into two separate pieces. For example, the polymer attached to the ingot or semiconductor wafer may have a CTE (coefficient of thermal expansion) that differs from that of the semiconductor workpiece. Cooling the first region of polymer and the ingot (or the first region of polymer and the semiconductor wafer) to a temperature below the critical temperature may apply mechanical stress to the ingot (or semiconductor wafer). The polymer may include a second region that does not overlap with the first region of the surface. The second region may surround the first region of polymer and may be sized such that, during cooling, at least a portion of the second region of polymer remains above the critical temperature, maintaining elasticity. This can reduce forces applied to the device frame. In one example, the semiconductor workpiece and the first region of polymer are cooled together using a cooling punch that does not directly contact the second region of polymer and / or only partially contacts the second region of polymer.

[0096] During the wafer splitting process, pressure may be applied to the semiconductor wafer 100. For example, a piston may apply pressure to the semiconductor wafer 100 having one or more epitaxial layers 102. The piston may be pushed toward the wafer 100 using compressed air, or only the weight of the piston may be applied to the wafer 100.

[0097] Cooling can be part of a temperature process that includes a first phase, during which the polymer and semiconductor workpiece undergo a temperature gradient from a starting temperature of 300°C or less but above room temperature to room temperature, and a second phase, during which cooling 830 is performed. Prior to the temperature process, one or more fillers (such as ZnO and / or carbon black) can be added to the polymer, which can increase the thermal conductivity of the polymer and reduce the slope of the polymer's storage modulus. During partial crystallization of the first region of the polymer, at least one crack propagates through the semiconductor workpiece along the separation region. Furthermore, during the splitting of the semiconductor wafer into two separate pieces, additional external force can be applied to the semiconductor workpiece by applying pressure to the semiconductor wafer.

[0098] Optionally, in a subsequent step, after the semiconductor workpiece is split into two separate wafers, the surface roughness of the separation surfaces of the two wafers may be reduced, each separation surface being a surface formed as at least one crack propagates along the separation region.

[0099] As described in the above disclosure, the crystal blank and semiconductor wafer can be SiC crystal blanks / SiC semiconductor wafers. However, the embodiments described herein are not intended to be limited to SiC crystal blanks and SiC wafers, but can be used with other semiconductor wafer technologies, such as silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), sapphire, etc.

[0100] Although the present disclosure is not limited in this regard, the following numbered examples illustrate one or more aspects of the present disclosure.

[0101] Example 1: An apparatus for attaching a polymer to a semiconductor workpiece during a cleavage process, the apparatus comprising a polymer and a frame, wherein the frame is connected to and surrounds the polymer, the polymer being configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when having a temperature above the critical temperature, and the polymer comprising a first region having a surface to which the semiconductor workpiece can be attached.

[0102] Example 2: The device of Example 1, further comprising a foil, wherein the foil is fixedly attached to the polymer and the frame, thereby connecting the polymer and the frame.

[0103] Example 3: The apparatus of Example 2, wherein the frame is a wafer ring and wherein the foil is a dicing foil.

[0104] Example 4. The device of Example 1, wherein the polymer is directly attached to the frame, thereby connecting the polymer and the frame.

[0105] Example 5: The device of Example 1, wherein the polymer includes a second region that does not overlap with and surrounds the first region of the polymer.

[0106] Example 6: The apparatus of Example 5, wherein the surface of the first zone has a substantially circular shape with a diameter of one of about 15 cm, about 20 cm, or about 30 cm.

[0107] Example 7: Apparatus according to example 5 or 6, wherein the surface of the second zone has a substantially annular shape, wherein the inner circle of the ring is given by the surface of the first zone, and wherein the outer circle of the ring has a diameter of at least 16 cm or at least 18 cm.

[0108] Example 8: A device according to any of the preceding examples, wherein the frame includes a flexible ring, wherein the flexible ring has substantially a circular shape with a first diameter, wherein the flexible ring includes three or more ring elements and corresponding three or more flexible attachment elements, wherein each flexible attachment element connects two corresponding ring elements of the three or more ring elements to each other to form the flexible ring, wherein when a force directed toward the center of the flexible ring is applied to the flexible ring, the flexible attachment elements contract so that the flexible ring has substantially a circular shape with a second diameter, and the second diameter is smaller than the first diameter.

[0109] EXAMPLE 9 The apparatus of Example 8, wherein the frame further comprises an outer ring, and wherein the flexible ring is removably attached to the outer ring.

[0110] Example 10: Use of the device according to any of Examples 1 to 9 in a splitting process.

[0111] Example 11: A method for splitting a semiconductor workpiece, the method comprising: attaching the semiconductor workpiece to a first region of a polymer surface of an apparatus, wherein the apparatus comprises a polymer and a frame, wherein the frame is connected to and surrounds the polymer, wherein the polymer is configured to undergo at least a partial glass transition when cooled to below a critical temperature and to be elastic when having a temperature above the critical temperature, wherein the polymer comprises the surface; and cooling the blank together with the first region of the apparatus to a temperature below the critical temperature.

[0112] Example 12: The method of Example 11, wherein the surface of the polymer includes a second region that does not overlap with the first region of the surface, and wherein during cooling, at least a portion of the second region is maintained at a temperature above the critical temperature.

[0113] Example 13: A method according to Example 11 or 12, wherein the semiconductor workpiece is attached to the device so that the outer surface of the semiconductor workpiece is placed on the device, and the distance from the outer surface to the separation region within the semiconductor workpiece is smaller than the surface of the semiconductor workpiece opposite to the outer surface.

[0114] EXAMPLE 14 The method of any of Examples 10 to 13, wherein the separation region has at least one altered physical property that increases thermomechanical stress within the separation region relative to the remainder of the semiconductor workpiece.

[0115] Example 15: A method according to any one of Examples 10 to 14, wherein cooling the crystal blank together with the first zone of the equipment to a temperature below the critical temperature causes an external force to be applied to the semiconductor workpiece, so that at least one crack propagates along the separation zone and the semiconductor workpiece is split into two separate crystal pieces.

[0116] Example 16: The method of any of Examples 10 to 15, wherein forming the separation region within the semiconductor workpiece comprises damaging material of the semiconductor workpiece at a target location within the semiconductor workpiece.

[0117] EXAMPLE 17: The method of Example 16, wherein damaging the material of the semiconductor workpiece at the target location within the semiconductor workpiece comprises generating a plasma in the material at the target location within the semiconductor workpiece.

[0118] EXAMPLE 18: The method of Example 17, wherein generating the plasma in the material at the target location within the semiconductor workpiece comprises focusing laser radiation at the target location within the semiconductor workpiece.

[0119] Example 19: The method of Example 16, wherein damaging material of the semiconductor workpiece at a target location within the semiconductor workpiece comprises implanting ions into the semiconductor workpiece at a depth corresponding to the target location within the semiconductor workpiece.

[0120] Example 20: The method of Example 19, wherein the ions are selected from the group consisting of nitrogen ions, phosphorus ions, hydrogen ions, and helium ions.

[0121] Example 21: The method of Example 19, wherein an implantation dose of the ions is selected such that a material of the semiconductor workpiece damaged by the implanted ions is amorphous or a cavity is generated.

[0122] Example 22: A method according to Example 16, wherein damaging the material of the semiconductor workpiece at a target location within the semiconductor workpiece includes: implanting ions into the semiconductor workpiece at a depth corresponding to the target location within the semiconductor workpiece; and after the ion implantation, focusing laser radiation at the target location within the semiconductor workpiece, wherein the implanted ions increase the absorption coefficient in the separation region at the wavelength of the laser radiation.

[0123] Example 23: The method of Example 15, wherein the external force is applied to the semiconductor workpiece by attaching the semiconductor workpiece to a polymer, and wherein the polymer has a coefficient of thermal expansion (CTE) that is different from a CTE of the semiconductor workpiece.

[0124] Example 24: The method of Example 15, wherein cooling causes the polymer to undergo a partial glass transition and / or partial crystallization.

[0125] Example 25: A method according to any one of Examples 11 to 24, wherein cooling is part of a temperature process, wherein the temperature further includes a first stage, during which the polymer and the semiconductor workpiece undergo a temperature gradient from a starting temperature to room temperature, the starting temperature being 300°C or lower but higher than room temperature before cooling.

[0126] Example 26. The method of any one of Examples 11 to 25, wherein a filler is added to the polymer.

[0127] Example 27: The method of Example 26, wherein the one or more fillers include ZnO and / or carbon black.

[0128] Example 28: The method of any one of Examples 11 to 27, further comprising chemically and / or physically treating a surface of the polymer and / or a surface of the semiconductor workpiece before attaching the semiconductor workpiece to the polymer.

[0129] Example 29. The method of Example 15, wherein at least one crack propagates during partial crystallization of the polymer that occurs during the temperature process.

[0130] Example 30: The method of Example 15, wherein during splitting the semiconductor workpiece into two separate wafers, an additional external force is applied to the semiconductor workpiece by applying pressure to the semiconductor workpiece.

[0131] Example 31: According to the method described in any one of Examples 11 to 30, the method further includes: after the semiconductor workpiece is split into two separate crystal pieces, reducing the surface roughness of the separation surfaces of the two crystal pieces, each separation surface is a surface formed as at least one crack propagates along the separation area.

[0132] Example 32: A method according to Example 15, wherein at least one altered physical property of the separation zone includes a plurality of microcracks that are at least partially disconnected from each other within the separation zone, and wherein the plurality of microcracks connect to each other in response to an external force to form at least one crack that propagates along the separation zone.

[0133] Example 33: An apparatus for attaching a polymer to a semiconductor workpiece during a cleaving process, the apparatus comprising a polymer and a frame, wherein the frame is directly connected to the polymer and surrounds the polymer, the polymer being configured to undergo at least a partial glass transition when cooled to below a critical temperature and to be elastic when having a temperature above the critical temperature, wherein the polymer includes a surface to which the semiconductor workpiece can be attached, and wherein the polymer has a diameter of at least 16 cm or at least 18 cm.

[0134] Example 34. The apparatus of Example 33, wherein the polymer has a diameter of at least 20 cm.

[0135] Example 35. The apparatus of Example 33, wherein the polymer has a diameter of at least 23 cm.

[0136] Example 36. The apparatus of Example 33, wherein the polymer has a diameter of at least 25 cm.

[0137] Example 37. The apparatus of Example 33, wherein the polymer has a diameter of at least 30 cm.

[0138] Example 38: The apparatus or method of any of the preceding examples, wherein the blank is a SiC blank, and / or wherein the semiconductor wafer is a SiC semiconductor wafer.

[0139] Although specific examples have been illustrated and described herein, it will be appreciated by those skilled in the art that a variety of alternative and / or equivalent embodiments 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 adaptation or variation of the specific examples discussed herein. Accordingly, it is intended that the present invention be limited only by the claims and their equivalents.

[0140] It should be noted that the methods and apparatus, including the preferred embodiments thereof, outlined in this document may be used alone or in combination with other methods and apparatus disclosed in this document. Furthermore, features outlined in the context of an apparatus also apply to the corresponding method, and vice versa. Furthermore, all aspects of the methods and apparatus outlined herein may be combined in any manner. In particular, features of the claims may be combined with one another in any manner.

[0141] It should be noted that the description and drawings merely illustrate the principles of the proposed method and system. 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 present invention and are included within its spirit and scope. Furthermore, all examples and embodiments summarized in this document are primarily and expressly intended to be used for explanatory purposes only, to help the reader understand the principles of the proposed method and system. Furthermore, all statements herein providing principles, aspects, and embodiments of the present invention and specific examples thereof are intended to encompass equivalents thereof.

Claims

1. An apparatus for attaching a polymer to a semiconductor workpiece during a cleaving process, the apparatus comprising a polymer and a frame, wherein: The frame surrounds the polymer, The polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when having a temperature above the critical temperature, The polymer includes a first region having a surface to which a semiconductor workpiece can be attached, and The frame and / or the polymer comprises at least one attachment element, wherein the polymer is directly attached to the frame via the at least one attachment element, thereby connecting the polymer and the frame.

2. The apparatus of claim 1 , wherein the thickness of the polymer in the first zone is at least 2 mm.

3. The device according to any of the preceding claims, wherein the frame comprises at least one attachment element protruding from the frame towards the polymer.

4. Device according to any of the preceding claims, wherein the at least one attachment element comprises or consists of hooks and / or holes in the material of the frame.

5. The apparatus of any preceding claim, wherein the frame comprises at least one attachment element, and wherein the polymer is molded to the at least one attachment element of the frame.

6. A device according to any preceding claim, wherein the polymer comprises a second region which does not overlap with and surrounds the first region of polymer.

7. Device according to the preceding claim, wherein the surface of the second zone has a substantially annular shape, wherein the inner circle of the ring is given by the surface of the first zone, and wherein the outer circle of the ring has a diameter of at least 16 cm.

8. The apparatus of any one of the preceding claims, wherein the frame comprises a flexible ring, wherein the flexible ring substantially has a first inner diameter, wherein the flexible ring comprises three or more ring elements and corresponding three or more flexible attachment elements, wherein each flexible attachment element connects two corresponding ones of the three or more ring elements to each other to form a flexible ring, Wherein when a force directed toward a center of the flexible loop is applied to the flexible loop, the flexible attachment element contracts such that the flexible loop substantially has a second inner diameter, the second inner diameter being smaller than the first inner diameter.

9. A method of cleaving a semiconductor workpiece, the method comprising: attaching a semiconductor workpiece to a surface of a first region of a polymer of an apparatus, wherein the apparatus comprises a polymer and a frame, wherein the frame is coupled to and surrounds the polymer, wherein the polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when having a temperature above the critical temperature, wherein the polymer comprises the surface; and The ingot or semiconductor is cooled together with the first zone of the apparatus to a temperature below the critical temperature.

10. The method according to the preceding claim, wherein the surface of the polymer comprises a second zone which does not overlap with the first zone of the surface, and wherein during cooling at least a portion of the second zone is maintained at a temperature above the critical temperature.

11. A method according to any of the two preceding claims, wherein the semiconductor workpiece is attached to the device so that an outer surface of the semiconductor workpiece is placed on the device, and the outer surface is at a smaller distance from the separation zone within the semiconductor workpiece than a surface of the semiconductor workpiece opposite to the outer surface.

12. An apparatus for holding a semiconductor workpiece during a cleaving process, the apparatus comprising a polymer and a frame, wherein: The framework is directly connected to the polymer and surrounds the polymer, The polymer is configured to undergo at least a partial glass transition when cooled below a critical temperature and to be elastic when having a temperature above the critical temperature, The polymer comprises a surface to which a semiconductor workpiece may be attached, and The polymer has a diameter of at least 16 cm.

13. The device according to the preceding claim, wherein the polymer has a diameter of at least 23 cm.

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