Method for transferring functional units, donor substrate and device for carrying out such method

Abstract

The invention relates to a method for transferring functional units (4, 4 ', 4 '', 4''', 4 '''') from a donor substrate (1) of an output functional unit (4, 4 ', 4 '', 4''', 4 '''') to an acceptor substrate (8) of a receiving functional unit (4, 4 ', 4 '', 4''', 4 ''''), in particular as a sub-step for constructing a product substrate, comprising: providing the donor substrate (1) and the acceptor substrate (8), the donor substrate (1) having a functional unit (4, 4 ', 4 '', 4''', 4 ''''), preferably a plurality of functional units (4, 4 ', 4 '', 4''', 4 ''''), and a separation layer (6), the separating layer is preferably integrated into a layer system (3); aligning the donor substrate (1) and the acceptor substrate (8) relative to each other by means of an alignment device; separating the separating layer (6) in the region of the functional units (4, 4 ', 4 '', 4''', 4 ''''), and removing the donor substrate (1) without the functional units (4, 4 ', 4 '', 4''', 4 ''''), the functional units (4, 4 ', 4 '', 4''', 4 '''') remaining on the acceptor substrate (8) or on the product substrate structure on the acceptor substrate (8) in order to form the product substrate.

Description

Technical Field

[0001] The present invention relates to a method for transferring functional units, a donor substrate for the method, and an apparatus for performing the method. Background Technology

[0002] The semiconductor industry is approaching its limits as miniaturization becomes increasingly difficult. The node size of transistors today is so small that further shrinking is becoming increasingly difficult, expensive, or even physically infeasible. Therefore, several years ago, efforts began not only to shrink functional units laterally, but also to arrange functional units in a three-dimensional manner.

[0003] Initially, the plan was to fabricate multiple functional layers stacked on top of each other, with the functional layers connected via TSVs (through silicon vias).

[0004] An improvement involves fabricating different functional units on different substrates. In particular, these units can be manufactured by different companies. For example, one company could specialize in microchip manufacturing, and a second company in memory chip manufacturing. These substrates are then aligned and bonded together. Bonding is preferably fusion bonding, especially hybrid bonding. Because each functional unit on the first substrate must be located at least near a functional unit on the second substrate, the grid along which the functional units are generated must be identical. If 10,000 functional units are generated on the first substrate, then 10,000 functional units must also exist on the second substrate. A serious drawback of these methods is that malfunctioning functional units are always bonded to opposing, functioning functional units. The chip formed by these two bonded functional units, subsequently separated from the substrate stack, is of course no longer functional and must be discarded. Therefore, it is impossible to use only the known-good-dies units and remove the malfunctioning units beforehand during the bonding process, since these units are, after all, part of the substrate. The method of bonding two substrates, especially wafers, to each other is also called the W2W method (wafer-2-wafer or wafer-to-wafer).

[0005] The improvement involves using a first substrate on which individual functional units are fabricated. The functionality of each individual functional unit on the substrate is checked. Then, using a chip-to-wafer bonding machine, the functional units on the second substrate, separated by a dicing process, are individually bonded to the functional units on the first substrate, but only if the functional units on the second substrate and the previously checked, separated functional units are functional. This ensures that the bonding process only occurs between functional units that are functioning correctly. The stacking process can continue with other functional units, resulting in a single substrate on which multiple sublayers of functional units are present. The resulting substrate is then either potted or otherwise protected before being separated into individual chips. For example, patent documents WO 2018 157 937 A1 and WO 2009 115 240 A1 illustrate such methods and apparatus. This method can significantly reduce waste. The disadvantage is that the separated functional units must be individually bonded to each other, which is time-consuming and costly. Another drawback is that the functional units are typically chips, i.e., potted dies. These chips are embedded in the potting compound and have solder balls on at least one side, but ideally at least contacts to allow for conductive connections with functional units on the substrate or other chips stacked thereon. The potting compound and solder balls unnecessarily increase the size of the resulting stacked functional units.

[0006] Therefore, a problem in the prior art is that functional units are typically chips or dies, i.e., pre-encapsulated dies, which in particular also have solder balls or at least electrical contacts of a certain height. Preferably, it is desirable to directly bond dies, especially dies serving as ultra-thin functional units. The die can be unilaterally or bilaterally active, i.e., having functional and / or contact portions on its front and / or rear sides.

[0007] Another problem is that the functional units typically differ from each other in their lateral dimensions, i.e., length and width. Therefore, it is desirable not only to stack the functional units in the third dimension, but also to optimally arrange the functional units in the plane.

[0008] Another issue lies in the transfer of functional units. The thinner the functional unit, the more difficult it is to transfer it from the donor substrate to the acceptor substrate. Even if the transfer itself is successfully performed through the bonding process, the functional unit still needs to be separated from the donor substrate. Because the functional unit is on an ultrathin substrate, the method steps must be performed in such a way that the functional unit is not damaged.

[0009] Another problem with the prior art is that the functional units generated on the acceptor substrate, especially those stacked, must also be separated from the acceptor substrate again in order to be finally encapsulated into the manufactured chip or die in the final process steps. Summary of the Invention

[0010] The present invention achieves the stated objective by means of the method for transferring functional units according to claim 1, the donor substrate according to claim 14, and the apparatus according to claim 15. Advantageous improvements of the invention are described in the dependent claims. All combinations of at least two features described in the specification, claims, and / or drawings also fall within the scope of the invention. Values ​​within the given range that fall within the mentioned limits should also be disclosed as limit values ​​and can be claimed in any combination.

[0011] According to a first aspect of the invention, a method is provided for transferring a functional unit from a donor substrate of an output functional unit to a receiver substrate of a receiving functional unit, particularly as a sub-step in constructing a product substrate, the method comprising:

[0012] - Provides a donor substrate and an acceptor substrate, wherein the donor substrate has functional units, preferably multiple functional units, and a separation layer, said separation layer preferably integrated into the layer system.

[0013] - The donor substrate and the acceptor substrate are aligned relative to each other using an alignment device.

[0014] - Separate the separation layer in the area of ​​the functional unit, and

[0015] - Remove the donor substrate that does not have functional units.

[0016] The product substrate is constructed by reserving functional units on the acceptor substrate or on the product substrate at the acceptor substrate location.

[0017] Contrary to common methods in the prior art, the present invention proposes that functional units are provided by a donor substrate, which itself is not part of the product substrate but serves to retain the functional units on a recipient substrate. Thus, when constructing the product substrate, particularly thin functional units can be placed on the recipient substrate without the need for additional components to stabilize the functional units. This correspondingly avoids components that occupy structural space during product substrate construction. Those skilled in the art will understand functional units, in particular, as structures with functional characteristics, i.e., active components. Examples include microchips, memory chips, LEDs, MEMS, etc. Therefore, the present invention enables ultra-thin functional units to be directly bonded to the product substrate structure or bonded to another ultra-thin functional unit. Furthermore, functional units can be arranged in a lateral plane with high packaging density. The ultra-thin functional units are preferably interconnected directly or via TSV (through silicon via).

[0018] The product substrate, in its manufactured state, preferably comprises a plurality of functional units, which are arranged, in particular, at a height offset from each other. It is also possible to combine the height-offset arrangement with laterally arranged functional units, especially different functional units, on a single plane. The product substrate is preferably constructed by sequentially arranging one or more functional units. Here, a dielectric or dielectric layer is deposited in an intermediate step to achieve height offset between the height-offset and, if necessary, laterally offset functional units in a layered manner. A method for transferring functional units is preferably used to construct the product substrate. The product substrate is then, for example, formed into a chip or a pre-chip stage.

[0019] In particular, the product substrate construction should be understood as the arrangement of layers that have been constructed in the process of the method for manufacturing the product substrate prior to all the layer combinations of the product substrate, preferably by means of the described method.

[0020] Furthermore, it is preferably proposed that the donor substrate has a first donor substrate portion and a second donor substrate portion. The first donor substrate portion serves particularly as a carrier, while the second donor substrate portion includes one or more functional units. A separation layer is preferably sandwiched between the first and second donor substrate portions, particularly along a stacking direction perpendicular to the main extension plane. The donor substrate may have an extension in a direction parallel to the main extension plane, said extension being greater than or comparable to the corresponding extension of the subsequent product substrate. For example, it is conceivable that the donor substrate is separated from a larger donor substrate structure. The donor substrate is constructed, for example, at least partially, monolithically, by means of epitaxy.

[0021] In particular, the separation layer is characterized in that it can be separated or dissolved in a targeted manner, especially at a specific time point and preferably within a defined range. For this purpose, a separation layer is preferably provided, which can be triggered by a trigger to induce separation or dissolution. Correspondingly, the separation layer is adapted to a corresponding trigger, such as a chemical or optical method, or coordinated with it.

[0022] Another aspect of the present invention is a method for constructing a product substrate, the method comprising:

[0023] - Provides a donor substrate and an acceptor substrate, wherein the donor substrate has functional units, preferably multiple functional units, and a separation layer, said separation layer preferably integrated into the layer system.

[0024] - The donor substrate and the acceptor substrate are aligned relative to each other using an alignment device.

[0025] - Separate the separation layer in the area of ​​the functional unit, and

[0026] - Remove the donor substrate that does not have functional units.

[0027] The functional units are retained on the acceptor substrate or on the product substrate structure to construct the product substrate. All the characteristics and advantages described for the transfer method can be similarly applied to the method of constructing the product substrate.

[0028] Preferably, the retained functional unit is bonded and / or a dielectric layer is applied on the acceptor substrate. Here, pre-bonding is preferably transitioned to permanent bonding. This is preferably set when the functional unit is placed on the product substrate. For example, bonding is performed via heating, which can be done before or after the separation layer. By applying the dielectric layer, a sublayer is preferably formed, extending alongside the functional unit in a plane parallel to the main extension plane. Subsequently, another functional unit can be retained on the functional unit and / or the dielectric layer. The product substrate is formed incrementally in this manner. Here, it is conceivable that the dielectric layer has a thickness substantially corresponding to the thickness of the functional unit. This can be achieved, for example, by removing a portion of the layer applied at the dielectric material, i.e., a portion of the dielectric layer.

[0029] Furthermore, it is preferably proposed that a contact be established between a donor substrate on one side and a acceptor substrate or product substrate structure on the other side, wherein the contact, particularly a direct contact, is established between the donor substrate and the acceptor substrate or product substrate structure via a contact side of the donor substrate, wherein a segment of the functional unit forms part of the contact side. In other words, the functional unit faces the acceptor substrate or product substrate when placed onto it. Thus, for example, the functional unit can be placed directly onto the product substrate structure or the acceptor substrate. Furthermore, it is feasible to directly access the functional unit before it is separated, thereby allowing functional testing. In particular, it is proposed that pre-bonding be induced by contact. This can be supported or induced, for example, by appropriate fabrication of the outer side of the acceptor substrate or product substrate structure.

[0030] In particular, it is proposed to separate the separation layers optically and / or chemically. Optical separation proves particularly advantageous here because it allows, for example, locally confined separation. Chemical dissolution proves advantageous in cases where the product substrate and / or acceptor substrate are opaque to light that would otherwise be available for separation.

[0031] Preferably, the separation layer is separated in a locally restricted manner. This allows, advantageously, the separation of only a single functional unit or a limited number of functional units from the donor substrate. This enables the individualized selection of functional units within a donor substrate having multiple functional units, which is particularly advantageous when one or a few functional units in the donor substrate are defective. The defective functional units can then be skipped, and only the functional units can be selectively transferred or retained.

[0032] Furthermore, it is preferably proposed that the separation layer and / or layer system comprises at least one sublayer made of inorganic material, particularly inorganic material. This provides a separation layer that is relatively easy to separate, for example by means of a laser, and which does not require additional cleaning steps. In a preferred embodiment of the method, the separation layer is proposed to be composed of a metal or nitride, preferably TiN. Inorganic separation layers composed of metals or nitrides are particularly suitable because they can also achieve stable bonding. Tin-based separation layers are particularly preferred.

[0033] The layer system includes at least one layer. The at least one layer is a release layer, which can be influenced by applying an external medium, preferably electromagnetic radiation, most preferably laser light, and most preferably infrared laser light, such that at least one substrate can be released from at least one side of the layer system. Other layers can function as bonding layers, absorption layers, absorption-enhancing layers, seed layers, growth layers, etc.

[0034] The layers of the layer system are preferably composed of at least one material from one of the following material categories:

[0035] - Dielectrics, especially

[0036] - Nitrogen compounds, especially

[0037] - TiN, CrN, TaN, AlN, NiN, Si3N4

[0038] - Carbides, especially carbon layers

[0039] - Oxides

[0040] - Less preferred polymers

[0041] - Conductor (Elektrikum), preferably

[0042] - Metals, especially

[0043] Cr, Al, Ta, Co, Ni, Mn, Fe, Au, Ga, Sn, Ge, W, Cu, In.

[0044] Preferably, the functional units are functionally tested before contact is established between the donor and acceptor substrates. This advantageously avoids bonding defective functional units. After all, product substrates manufactured in this way are unusable due to their lack of functionality. Therefore, the scrap of defective product substrates can be reduced.

[0045] Furthermore, it is preferable that multiple functional units are arranged on the acceptor substrate in a height-staggered manner, and especially also staggered from each other. This gradually realizes the product substrate structure, and ultimately achieves a product substrate with functional units arranged in three dimensions.

[0046] Furthermore, it is preferably proposed that the functional unit is part of a plurality of functional units, which are particularly disposed on the same donor substrate, preferably simultaneously or sequentially, on the recipient substrate and / or on the product substrate structure. In particular, a portion of the functional units is transferred from the plurality of functional units, i.e., at least one functional unit is transferred.

[0047] In particular, it is proposed that lasers, especially pulsed lasers, be used for separation. In a preferred embodiment of the method, the laser beam has a wavelength between 0.1 μm and 500 μm, preferably between 0.2 μm and 100 μm, more preferably between 0.3 μm and 50 μm, most preferably between 0.5 μm and 10 μm, and most preferably between 1 μm and 2.5 μm. In this way, the separation layer can be irradiated particularly effectively and specifically. The carrier substrate is preferably transparent to the laser beam.

[0048] In a preferred embodiment of the method, the pulse energy of the laser beam is proposed to be between 0.01 μJ and 128 μJ, preferably between 0.125 μJ and 64 μJ, more preferably between 0.25 μJ and 32 μJ, most preferably between 0.5 μJ and 16 μJ, and completely preferably between 1 μJ and 8 μJ. It has been proven that these pulse energies can prevent damage to the product substrate. In a preferred embodiment of the method, the pulse duration of the laser beam is proposed to be between 10000 ps and 1 ps, preferably between 1000 ps and 1 ps, more preferably between 500 ps and 1 ps, most preferably between 100 ps and 1 ps, and completely preferably between 50 ps and 1 ps. The pulse duration allows for targeted action on separation.

[0049] Furthermore, it is preferred that the functional unit is part of a plurality of functional units, which are retained on the acceptor substrate from the same donor substrate, preferably simultaneously or sequentially.

[0050] Preferably, the product substrate or product substrate structure is detached from the recipient substrate via a separation layer on the recipient substrate side. This provides the manufactured product substrate, in particular without damaging or losing the recipient substrate. It is also conceivable that the product substrate structure can be transferred for further processing before the final product substrate structure is manufactured.

[0051] Alternatively, it is conceivable that the product substrate remains on the acceptor substrate, thereby forming a new product substrate. In other words, the acceptor substrate becomes part of the product substrate. The acceptor substrate can also have functionality or functional units. However, it is preferable that the product substrate and the acceptor substrate be separated, because this allows the acceptor substrate to be reused.

[0052] Specifically, it is proposed that the functional unit has a thickness measured perpendicular to the main extension plane, said thickness being less than 50 μm, preferably less than 25 μm, particularly preferably less than 1 μm or even less than 100 nm, wherein the functional unit is preferably encapsulated. This advantageous method has proven particularly advantageous for such ultrathin functional units, since the functional units, due to their reduced thickness, lack sufficient self-stability to allow for individualized transport. In particular, the ultrathin functional unit can also be a so-called 2D material.

[0053] Preferably, the method includes the following steps:

[0054] In a first method step, a donor substrate is manufactured, which is composed of or combined with a stabilized first donor substrate portion, a layer system, and a second donor substrate portion having functional units. The layer system has at least one separation layer that allows the functional units to be separated from the first donor substrate portion, particularly selectively.

[0055] In the second method step, the donor substrate is aligned relative to the recipient substrate. Specifically, the functional units of the donor substrate are aligned relative to alignment marks and / or relative to additional functional units already present on the recipient substrate. Alignment is preferably performed optically, particularly by means of an alignment device. Alignment can be performed face-to-face, back-to-back, face-to-back, or back-to-face methods.

[0056] In the third method step, the donor substrate is brought into contact with the acceptor substrate. This contact is a pre-bonding process. The surfaces of the donor and / or acceptor substrates may be hydrophilized, in particular, to produce a more efficient pre-bonding.

[0057] In the fourth method step, the separation layer within the layer system is subjected to chemical and / or physical action. Preferably, the separation layer is loaded using a laser, causing the functional units to separate from the donor substrate. For example, the separation layer is evaporated or sublimated. The action is preferably selective, i.e., only functionally intact units detach from the donor substrate. Ideally, all functional units from the donor substrate are transferred.

[0058] In the fifth step of the method, the donor substrate is removed from the acceptor substrate. At this point, the transferred functional units are located on the acceptor substrate. It is feasible to arrange functional units of different sizes and functions side-by-side and bond them to the acceptor substrate. The corresponding functional units are preferably ultrathin. Therefore, another donor substrate with additional functional units can contact the partially fitted acceptor substrate, and the additional functional units are bonded to the acceptor substrate.

[0059] A heat treatment is performed in a preferred, optional sixth method step, which permanently bonds the functional units. It is also conceivable that this heat treatment step is performed after the third or fourth method steps, depending on the strength of the pre-bonding. The stronger the pre-bonding, the later the heat treatment can be performed, as the risk of functional unit displacement is lower.

[0060] In the seventh method step, the functional units are dielectrically embedded on the acceptor substrate. All common methods can be used for this. Since it is technically difficult to deposit the dielectric material to be exactly the same thickness as the functional unit, and since functional units of varying thicknesses may exist in the plane, the dielectric material is deposited such that the resulting dielectric layer has a thickness greater than the thickest functional unit. Preferably, after the deposition process, the dielectric layer is back-side thinned and / or back-side polished to the desired thickness. Vias can then be created. In particular, in the accompanying drawings, the region above the functional units is explicitly described as a connecting layer. It is conceivable that the connecting layers are made of a different material than the dielectric layer in which the functional units are embedded. However, they are preferably made of the same material and deposited using only one method step.

[0061] An exemplary second method is the D2W (Die-to-wafer) method, in which a D2W or C2W bonding machine is used to align and bond individual dies.

[0062] In the first method step, a donor substrate is manufactured, which comprises a stabilized first donor substrate portion, a layer system, and a second donor substrate portion having functional units. The layer system has at least one separation layer that allows the functional units to be separated from the donor substrate, particularly selectively. The donor substrate is then separated. A plurality of donor substrate units are then present, each of which can be understood as a donor substrate in the sense of this invention.

[0063] A C2W bonding machine is used in the second method step. The bonding head of the C2W bonding machine receives the donor substrate unit and aligns it relative to its position on the recipient substrate. In particular, the functional units of the donor substrate unit are aligned relative to alignment marks and / or relative to another functional unit already present on the recipient substrate.

[0064] In the third method step, the donor substrate monolith is brought into contact with the acceptor substrate. This contact is a pre-bonding. The surfaces of the donor substrate monolith and / or the acceptor substrate can be hydrophilicallyized in particular to produce a more efficient pre-bonding.

[0065] In the fourth method step, the separation layer within the layer system is subjected to chemical and / or physical action. Preferably, the separation layer is applied using a laser, causing the functional units to separate from the donor substrate units. For example, the separation layer is evaporated or sublimated. An advantage over the first method is that it uses only those donor substrate units where the functional units are fault-free.

[0066] In the fifth step of the method, the donor substrate portion located above the layer system is removed from the functional unit fixed on the acceptor substrate. The transferred functional unit now resides on the acceptor substrate. It is feasible to arrange functional units of different sizes and functions side-by-side and bond them to the acceptor substrate. Targeted positioning in the lateral plane is particularly straightforward when using a C2W bonding machine.

[0067] A heat treatment is performed in a preferred, optional sixth method step, which permanently bonds the functional units. It is also conceivable that this heat treatment step is performed after the third or fourth method steps, depending on the strength of the pre-bonding. The stronger the pre-bonding, the later the heat treatment can be performed, as the risk of functional unit displacement is lower.

[0068] In the seventh method step, the functional unit is dielectrically embedded on the acceptor substrate. Dielectric embedding can be performed by various methods, such as and preferably by CVD (chemical vapor deposition), PVD (physical vapor deposition), sol-gel methods, and less preferably by ALD (atomic layer deposition) and molecular beam epitaxy. However, embedding into a polymer is also conceivable.

[0069] In most cases, the deposited dielectric layer covers the functional cells, therefore back-side thinning must be performed down to the functional cells. Back-side thinning is performed by grinding and / or polishing processes. Etching back is also conceivable. The method steps described are known to those skilled in the art. These method steps will not be mentioned again in the following text as they do not contribute to understanding the invention.

[0070] In one improved embodiment, functional units detached from the donor substrate align themselves via a self-assembly process after being transferred to the acceptor substrate. This self-alignment can be induced and / or supported by a variety of chemical and / or physical conditions.

[0071] In another preferred embodiment, pre-bonding of the functional unit is performed on a mesa (a trapezoidal structure). The mesa may, in particular, be provided with a thin water film. If the functional unit is placed on one of the mesa protrusions, the functional unit is centered relative to the mesa through an energy-minimizing process. The thickness of the mesa is less than 1 mm, preferably less than 0.5 mm, more preferably less than 0.1 mm, most preferably less than 0.05 mm, and most preferably less than 0.01 mm. In particular, the mesa is intended for in-situ fixation of the water film, as the water film is fixed in place by the edges of the mesa.

[0072] In another preferred embodiment, the surface of the acceptor substrate is chemically and / or physically masked. The mask is understood to prepare the surface in such a way that at least two regions with different chemical and / or physical properties are formed. For example, it is conceivable that the regions to which functional units are to be immobilized are hydrophilic, while the surrounding regions are hydrophobic. Another possibility is to produce regions with high adhesion strength, while the surrounding regions have very low adhesion strength. Such a mask can be readily produced using a combination of photolithography, imprint lithography, and coating techniques.

[0073] The latter two implementations can also be advantageously combined with each other. Thus, it is conceivable that the surface of the protrusion is hydrophilic to better fix and flatten the water film, while the surrounding environment separated from the protrusion is hydrophobic, i.e., water-repellent.

[0074] Another subject of the invention is a donor substrate for use in the method according to the invention, wherein the donor substrate has functional units and a separation layer. All the advantages and characteristics described for the method can be similarly applied to the donor substrate, and vice versa.

[0075] Another subject of the invention is an apparatus for performing the method according to the invention, wherein the apparatus has at least one control device for coordinating the method. All the advantages and features described for the method can be similarly applied to the apparatus, and vice versa. Attached Figure Description

[0076] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the accompanying drawings. The drawings show:

[0077] Figure 1 A schematic partial and side view of the donor substrate is shown.

[0078] Figure 2 A schematic partial and side view of the receptor substrate is shown.

[0079] Figure 3a The first method steps according to the first method of the present invention are shown.

[0080] Figure 3b The second method steps according to the first method of the present invention are shown.

[0081] Figure 3c The third method step according to the first method of the present invention is shown.

[0082] Figure 3d The fourth method step according to the first method of the present invention is shown.

[0083] Figure 3e The fifth method step according to the first method of the present invention is shown.

[0084] Figure 3f The sixth method step according to the first method of the present invention is shown.

[0085] Figure 3g The seventh method step of the first method according to the present invention is shown.

[0086] Figure 3h The eighth method step of the first method according to the present invention is shown.

[0087] Figure 4a The first method steps of the second method according to the present invention are shown.

[0088] Figure 4b The second method steps according to the second method of the present invention are shown.

[0089] Figure 4c The third method steps of the second method according to the present invention are shown.

[0090] Figure 4d The fourth method step according to the second method of the present invention is shown.

[0091] Figure 4e The fifth method step of the second method according to the present invention is shown. Detailed Implementation

[0092] In the accompanying drawings, the same components or components with the same function are indicated by the same reference numerals.

[0093] Figure 1 The diagram shows a schematic partial and side view of a donor substrate 1, which is constructed from a layer system 3 having a separation layer 6, a first donor substrate portion 2, and a second donor substrate portion 2' having functional units 4. The donor substrate 1 can be manufactured in any manner and method. Preferably, the separation layer 6, the first donor substrate portion 2, and the second donor substrate portion 2' are sandwiched together, wherein the separation layer 6 is disposed between the first donor substrate portion 2 and the second donor substrate portion 2'.

[0094] A first exemplary method for fabricating the donor substrate 1 uses an oxide layer. An oxide layer 7 is deposited on a second initial substrate, which subsequently becomes a second donor substrate portion 2', and functional units 4 are already present on or integrated therein on the second initial substrate, the oxide layer subsequently becoming part of a layer system 3. Simultaneously, at least one release layer 6 is deposited on a first initial substrate, which subsequently becomes a first donor substrate portion 2. It is also contemplated that oxide 7 is deposited above the release layer 6 as well. The first and second initial substrates are then bonded together to form the donor substrate 1. Subsequently, at least a portion of the second initial substrate is thinned or removed, particularly on the side opposite to the first initial substrate, down to the functional unit 4. It is also contemplated that a SmartCut process is used. The functional unit 4 can be fabricated before and / or after bonding. However, methods for fabricating functional units 4 are known to those skilled in the art. Figure 1 Numerous methods of donor substrate 1 are shown in the figure.

[0095] A second method for manufacturing the donor substrate 1 involves forming at least a separation layer 6 on the first donor substrate portion 2 as part of a layer system 3, and forming a second donor substrate portion 2' on the layer system 3 by means of epitaxy. In this case, a bonding process is not required to produce the donor substrate 1 having functional units 4. Therefore, the donor substrate 1 is constructed, for example, monolithically.

[0096] The first donor substrate portion 2 is primarily used for stabilization, i.e., as a carrier. The layer system 3 typically comprises multiple layers of hard material, particularly dielectric hard material layers. However, it is also conceivable that at least one of the layers is dielectric and organic. Preferably, all dielectric hard material layers comprise nitrides, oxides, or carbides. The layer system 3 has at least one separation layer 6, which causes the first donor substrate portion 2 to separate from the second donor substrate portion 2' by chemical and / or physical means, preferably by laser. When using a laser, the donor substrate portion 2 and all other layers of the layer system 3 up to the separation layer 6 must be transparent to the laser radiation used. The separation layer 6 itself should have the highest possible absorption for the laser used.

[0097] Functional unit 4 preferably has an electrical contact portion 5, which allows it to establish an electrical connection with another functional unit 4.

[0098] The functional units 4 at the donor substrate 1 can all be tested before the bonding process to identify known-good-dies or defective functional units 4. In a further method, only the known-good-dies functional units 4 are transferred, i.e., a selective transfer process is performed.

[0099] Figure 1 The enlarged view shows a schematic partial and side view of the layer system 3, which includes a release layer 6 and two oxide layers 7. In the specific case, the release layer 6 is first deposited on the first donor substrate portion 2, and the oxide layer 7 is deposited on the release layer 6 to increase the bonding strength. The second oxide layer 7 is deposited on the second donor substrate portion 2'. Then, the donor substrate portions 2, 2' are bonded to each other via their oxide layers 7. The layer system 3 shown is only one of many possibilities. Another possibility is that only the release layer 6 is deposited on the donor substrate portion 2 and directly bonded to the oxide layer 7 of the donor substrate portion 2'. Another possibility would be to construct the donor substrate 1 completely monolithically, fabricate the layer system 3 with at least one release layer 6 on the donor substrate portion 2, and then produce the donor substrate portion 2' by a growth process, particularly epitaxial growth. It is feasible to fabricate the functional unit 4 in the second donor substrate portion 2' by epitaxial growth. In the case of monolithic construction, no bonding step is required to produce the donor substrate 1, and the oxide layer 7 is at least not used for bonding. It is conceivable that an oxide layer is used for the growth process during the epitaxial fabrication of the second donor substrate portion 2'.

[0100] Figure 2The diagram shows schematic partial and side views, as well as a partial enlarged view, of a acceptor substrate 8, which consists of a acceptor substrate portion 9 and a layer system 3 formed thereon. In this simplified case, the layer system 3 consists of only a single separated layer 6 on the acceptor substrate side. It is also conceivable, in this case, that the layer system 3 is constructed from multiple layers performing different tasks. Using the layer system 3, functional units 16 subsequently built on the donor substrate 8 can be stacked (see, for example...) Figure 3h The functional unit stack 16 is separated from the acceptor substrate portion 9 so that it can be encapsulated in further process steps. It is also conceivable that the acceptor substrate 8 does not have the layer system 3, and in particular, does not have the separation layer 6 on the acceptor substrate side. However, to separate the functional unit stack 16, another method must be applied, especially the acceptor substrate 8, particularly acceptor substrate portion 9. This causes damage to the acceptor substrate 8, which is associated with significant costs. By using the layer system 3 with the separation layer 6 on the acceptor substrate side, the functional unit stack 16 can subsequently be separated from the acceptor substrate 8, and the acceptor substrate 8 can be reused. It is also conceivable that the acceptor substrate 8 does not need to be removed. In particular, the acceptor substrate itself can have additional functional units 4, or simply become part of the subsequent functional unit stack 16 by being vertically separated together.

[0101] Figure 3a The illustration shows a first method step according to a first method of the present invention, wherein a donor substrate 1 is provided. The donor substrate 1 includes at least one functional unit 4 and a layer system 3. The layer system 3 includes at least one separation layer 6 (not shown, see [link]). Figure 1 ).

[0102] Figure 3b A second step of the exemplary first method according to the invention is shown, wherein the donor substrate 1 is aligned relative to the (not yet equipped) recipient substrate 8. Alignment marks on the donor substrate 1 and / or recipient substrate 8 are not drawn. Alignment is performed, for example, by optical device 17. The recipient substrate 8 shown may have been treated such that it already has functional units in its initial state. To keep the figures as simple as possible, a diagram of the treated recipient substrate 8 is omitted. Therefore, the recipient substrate 8 is shown as an untreated substrate.

[0103] Figure 3c A third step of an exemplary first method according to the invention is shown, wherein the donor substrate 1 is bonded to the acceptor substrate 8. Because the surfaces of the donor and acceptor substrates are dielectric, the bonding is direct. The surfaces of the donor and / or acceptor substrates may have been chemically and / or physically treated, particularly hydrophilicated.

[0104] Figure 3dA fourth step of an exemplary first method according to the invention is shown, wherein the layer system 3, particularly the separation layer 6 contained within the layer system 3, is acted upon. Preferably, this is a thermal action, particularly by electromagnetic radiation, most preferably generated by a laser 18. By using the laser 18, localized and therefore particularly selective action, i.e., limited to a clearly defined surface, is feasible. The figure shows a laser beam 19 transmitted through the donor substrate 1. It is conceivable that the laser beam 19 acts via the donor substrate 1 and / or the acceptor substrate 8. However, in a further step of the method, multiple functional units 4 are stacked on the acceptor substrate 8, making transmission of laser radiation 19 through the acceptor substrate 8 no longer feasible or only limitedly feasible. Therefore, the laser beam 19 is preferably focused onto the layer system 3, particularly onto the separation layer 6, through the donor substrate 1.

[0105] Figure 3e A fifth step of the exemplary first method according to the invention is shown, wherein the donor substrate 1 is again removed from the recipient substrate 8. Only the transferred functional units 4 are shown exemplary at the recipient substrate 8 to highlight the selectivity of the method. In a production environment, it is preferable to transfer all (functionally intact) functional units 4 of the donor substrate 1 to the recipient substrate 8. If some functional units of the donor substrate 1 are damaged, the missing functional units at the recipient substrate are supplemented by additional functional units of another donor substrate (not shown). Furthermore, it is possible for additional donor substrates 1'', 1''' (not shown) with additional functional units of other sizes, properties, shapes, or functions to be transferred to the recipient substrate. For clarity, illustrations of these additional functional units are also omitted.

[0106] Figure 3f A sixth method step of an exemplary first method according to the present invention is shown, wherein heat treatment is performed. This method step may also have been performed in a third method step (see [link]). Figure 3c After or in the fourth method step (see...) Figure 3d Then it is executed. Heat treatment is used to convert pre-bonded bonds into permanent bonds.

[0107] Figure 3g A seventh method step of an exemplary first method according to the invention is shown, wherein the functional unit 4 is embedded in the dielectric layer 11. This method step creates a new acceptor substrate surface on which some new functional units 4 can be fixed. Typically, the dielectric layer 11 is deposited over the functional units and must be back-side thinned in a further method step, particularly until the functional units are no longer covered by the applied dielectric layer. Back-side thinning is preferably performed by means of CMP (chemical mechanical polishing). This method step is not explicitly shown. Figure 3gOnly the final result of dielectric layer 11 deposition is shown. It is also conceivable that if electrical contacts 5 are not already present on the now exposed surface, functional unit 4 must be equipped with electrical contacts 5 after backside thinning. All method steps for generating such contacts are also omitted from the diagram. Figure 3g This appears to indicate that the dielectric layer 11 has been thinned back to the height of the functional unit 4, which is impossible or extremely difficult to achieve during manufacturing. Preferably, the deposited dielectric layer 11 is not thinned back to expose the functional unit 4, but rather minimally covers the functional unit (see [link to documentation]). Figure 3h (Enlarged view on the left). If dielectric layer 11 still needs to be thinned on the back side to functional unit 4, then further overlays can be applied using interconnect layer 21 (see...). Figure 3h (The enlarged alternative view on the right) is feasible. In another particularly preferred embodiment, the back side of the dielectric layer 11 is thinned down to the functional unit 4, and the functional unit 4 of the next plane is in direct contact with the functional unit 4 of the plane below it. If future improvements to the manufacturing process are desired, this process flow could enable a more compact and thinner final product, i.e., a product substrate.

[0108] Figure 3h The eighth method step of the exemplary first method according to the present invention and its final result are shown. Multiple functional units 4, 4', 4'', 4''', 4'''' are arranged staggered in height and partially disposed in the lateral plane (4'', 4'''). For clarity, the different functional units 4, 4', 4''', 4'''' are shown at different gray levels. Figure 3hTwo possible enlarged views of functional units 4, 4', 4'', 4''', 4'''' are also shown so that electrical contacts 5 can be shown, via which functional units 4, 4', 4'', 4''', 4'''' are connected to each other. The first left enlarged view shows the most common situation encountered in industry, where the dielectric layer 11 is not completely back-thinned to the height of functional units 4, 4', 4'', 4''''. Through-hole or TSV (through silicon via) 20 allows contact of functional units 4, 4', 4''', 4''''' with different planes through the dielectric layer 11. The second right enlarged view shows an alternative (symbol v for mathematical ODER), where the dielectric layer 11 is back-thinned to functional units 4, 4', 4''', 4'''''. Then, an interconnect layer 21 is deposited over the dielectric layer 11 and the functional units 4, 4', 4'', 4''', 4''''. The interconnect layer 21 may be formed of the same or different material as the dielectric layer 11. Alternatively, it is conceivable to combine the two methods, i.e., thinning the back side of the dielectric layer 11 to slightly above the functional units 4, 4', 4''', 4'''', and then additionally depositing the interconnect layer 21 (not shown). The fabrication of the vias 20 and the additional printed conductors can be performed, in particular, using a double damask process. Such feasibility is known to those skilled in the art and will not be elaborated upon here, as it does not contribute to the inventive concept itself. It is also conceivable that functional units 4, 4', 4'', 4''', 4'''' are stacked vertically and directly connected to each other, thus completely or at least partially omitting the fabrication of the dielectric layer 11 and / or interconnect layer 21 and vias 20 deposited above the functional units 4, 4', 4'', 4''', 4''''. The collection of the functional units 4, 4', 4''', 4'''' forms a functional unit stack 16, which can then be used as a chip. The functional unit stack is separated from the acceptor substrate 8, possibly potted and equipped with contacts or solder balls. It is also conceivable that the new functional unit stack 16 is directly reprocessed further according to one of the methods described in the invention. The acceptor substrate 8 thus obtained can then be separated and further processed, for example, into a chip such as 15 (see...). Figure 5 The final product of ).

[0109] The following diagram was intentionally chosen, in which the bottommost functional unit 4 has a smaller lateral extension than the functional unit 4' bonded to it, to demonstrate the feasibility of the method. In manufacturing, it is possible that the bottommost functional unit 4 has the largest lateral dimension, while the functional units 4', 4'', 4''', and 4'''' stacked above it have progressively smaller lateral dimensions as the distance from functional unit 4 increases. Furthermore, it can be seen that two functional units 4''' and 4'''' are stacked to the right of functional unit 4', while only a single functional unit 4'' is present on the left.

[0110] Figure 4a The first method step of a second exemplary method according to the invention is shown, wherein at least one donor substrate unit 12 is separated from a larger donor substrate 1 (not shown). The donor substrate unit is itself the donor substrate 1.

[0111] Figure 4b A second method step according to a second exemplary method of the invention is shown, wherein the donor substrate unit 12 is fixed behind the bonding head 13 of a chip-to-wafer bonding machine (not shown) and positioned above the recipient substrate 8. Positioning can be performed again optically, particularly by means of alignment marks, and / or computer-controlled. The recipient substrate 8 shown may have been processed so that it inherently possesses functional units in its initial state. To keep the figures as simple as possible, a diagram of the processed recipient substrate 8 is omitted. Therefore, the recipient substrate 8 is shown as an unprocessed substrate.

[0112] Figure 4c A third method step of the second exemplary method according to the invention is shown, wherein the donor substrate monolith 12 is bonded to the acceptor substrate 8. Because the surfaces of the donor substrate monolith and the acceptor substrate are dielectric, the bonding is direct. The surfaces of the donor substrate monolith and / or the acceptor substrate may have been chemically and / or physically treated, particularly hydrophilicated.

[0113] Figure 4dThe figure illustrates a fourth step of the second method according to the invention, wherein the layer system 3, particularly the separation layer 6 contained within the layer system 3, is acted upon. Preferably, this is a thermal action, particularly by electromagnetic radiation, most preferably generated by the laser 18. The selectivity of the second method lies in the use of a single donor substrate unit 12, whereas in the first method it was selectively defined by the use of a laser. The figure shows a laser beam 19 transmitted through the donor substrate unit 12. It is conceivable that the laser beam 19 acts via the donor substrate unit 12 and / or the acceptor substrate 8. However, in a further step of the method, multiple functional units 4 are stacked on the acceptor substrate 8, making it no longer feasible or only limitedly feasible for the laser radiation 19 to transmit through the acceptor substrate 8. Therefore, the laser beam 19 is preferably focused onto the layer system 3, particularly onto the separation layer 6, through the donor substrate unit 12.

[0114] Figure 4e A fifth step of the second method according to the invention is shown, wherein the donor substrate unit 12 is removed again from the recipient substrate 8. Only one transferred functional unit 4 at the recipient substrate 8 is shown by way of example to highlight the selectivity of the method. In a production environment, it is preferable to transfer multiple (functional) functional units 4 of multiple donor substrate units 12 onto the recipient substrate 8. If a functional unit of a donor substrate unit 12 is damaged, the donor substrate unit is not removed from the set of all donor substrate units 12 at all. It is also possible to transfer additional donor substrate units 12', 12'' (not shown) with additional functional units of other sizes, properties, shapes, or functions onto the recipient substrate 8. For clarity, the illustration of the additional functional units 4 is also omitted.

[0115] The other steps of the second method are described in accordance with the accompanying drawings. Figure 3f , 3g The steps are the same as those of the first method in 3h, and will not be elaborated here.

[0116] Figure 5 A schematic diagram of one of many feasible end products is shown, namely a chip 15 encapsulated in potting compound 13 and equipped with solder balls 14. The contact between the two intermediate solder balls 14 and the functional unit 4 is not explicitly shown. Other end products are conceivable, in which flat contacts (pads) are used instead of solder balls 14; end products not encapsulated in potting compound, etc.

[0117] List of reference numerals

[0118] 1. Donor substrate

[0119] 2 First donor substrate portion

[0120] 2' Second donor substrate portion

[0121] 3-layer system

[0122] 4, 4', 4'', 4''', 4'''' Functional Unit

[0123] 5 Electrical Contacts

[0124] 6 separation layers

[0125] 7 Oxide Layer

[0126] 8-receptor substrate

[0127] 9-receptor substrate portion

[0128] 10 solder balls

[0129] 11 dielectric layers

[0130] 12 donor substrate single piece

[0131] 13-key connector

[0132] 14 potting materials

[0133] 15 chips

[0134] 16-functional-unit stack

[0135] 17 Optical Devices

[0136] 18 lasers

[0137] 19 laser beams

[0138] 20 through-hole (TSV)

[0139] 21. Interconnect layer

Claims

1. A method for transferring functional units (4, 4', 4'', 4''', 4'''') from a donor substrate (1) that outputs the functional units (4, 4', 4'', 4''', 4'''') to a recipient substrate (8) that receives the functional units (4, 4', 4'', 4''', 4''''), particularly as a sub-step for constructing a product substrate, the method comprising: - Provide a donor substrate (1) and an acceptor substrate (8), wherein the donor substrate (1) has functional units (4, 4', 4'', 4''', 4''''), preferably multiple functional units (4, 4', 4'', 4''', 4''''), and a separation layer (6), wherein the separation layer is preferably integrated into the layer system (3); - The donor substrate (1) and the acceptor substrate (8) are aligned relative to each other by means of an alignment device; - Separate the separation layer (6) in the region of the functional unit (4, 4', 4'', 4''', 4''''); as well as - Remove the donor substrate (1) that does not have the said functional units (4, 4', 4'', 4''', 4''''). The functional units (4, 4', 4'', 4''', 4''') are left on the receptor substrate (8) or on the product substrate structure at the receptor substrate (8) to construct the product substrate.

2. The method according to claim 1, wherein the retained functional units (4, 4', 4'', 4''', 4'''') are bonded and / or a dielectric layer is applied on the acceptor substrate (8).

3. The method according to any one of the preceding claims, wherein a contact is established between the donor substrate (1) on one side and the acceptor substrate (8) or the product substrate structure on the other side, wherein the contact, particularly a direct contact, is established between the donor substrate (1) and the acceptor substrate (8) or the product substrate structure via a contact side of the donor substrate (1), wherein a segment of the functional unit (4, 4', 4'', 4''', 4'''') forms part of the contact side.

4. The method according to any one of the preceding claims, wherein the separation layer (6) is optically and / or chemically separated.

5. The method according to any one of the preceding claims, wherein the separation layer (6) is partially and restrictedly separated.

6. The method according to any one of the preceding claims, wherein the separation layer (6) and / or the layer system comprises at least one sublayer made of inorganic material, particularly inorganic material.

7. The method according to any one of the preceding claims, wherein the functional units (4, 4', 4'', 4''', 4''') are functionally tested prior to the establishment of the contact between the donor substrate (2) and the acceptor substrate (8).

8. The method according to any one of the preceding claims, wherein a plurality of functional units (4, 4', 4'', 4''', 4'''') are disposed on the receptor substrate (8) or on the product substrate construction at a height offset from each other.

9. The method according to any one of the preceding claims, wherein a laser, particularly a pulsed laser, is used for separation.

10. The method according to any one of the preceding claims, wherein the functional unit (4, 4', 4'', 4''', 4''') is a portion of a plurality of functional units (4, 4', 4'', 4''', 4''') which are preferably simultaneously or sequentially present on the acceptor substrate (8) from the same donor substrate (1).

11. The method according to any one of the preceding claims, wherein a donor substrate (1) is manufactured in the preparation step, and the functional units (4, 4', 4'', 4''', 4'''') are formed on the contact side of the donor substrate, preferably a plurality of functional units (4, 4', 4'', 4''', 4'''').

12. The method according to any one of the preceding claims, wherein the product substrate or the product substrate configuration is detached from the recipient substrate (8) via a separation layer (6) on the recipient substrate side.

13. The method according to any one of the preceding claims, wherein the functional unit (4, 4', 4'', 4''', 4'''') has a thickness measured perpendicular to the main extension plane, said thickness being less than 50 μm, preferably less than 25 μm, and particularly preferably less than μm or even less than 100 nm, wherein said functional unit (4, 4', 4'', 4''', 4'''') is preferably encapsulated.

14. A donor substrate (1) for use in the method according to any one of the preceding claims, wherein the donor substrate (1) comprises the functional units (4, 4', 4'', 4''', 4''''), preferably a plurality of functional units (4, 4', 4''', 4''''), and the separation layer (6).

15. An apparatus for performing the method according to any one of claims 1 to 13, the apparatus comprising at least one control means for coordinating the method according to any one of claims 1 to 13.

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