System and method for die bonding self-alignment

Abstract

Existing die-to-wafer bonding tools use guided alignment to position the dies. A donor die position and its bonding location on an acceptor wafer are measured, and used as input for a bonding transfer mechanism. The measurements and the transfer mechanism contribute to placement errors. Die-to-wafer bonding accuracy requirements are increasing, with placement accuracy down to 50 nm and below often required. Achieving this accuracy with existing die-to-wafer bonding tools is challenging. As a result, new systems and methods for die bonding self-alignment have been developed. As with guided alignment, a transfer mechanism moves the donor die in proximity to a desired acceptor location on an acceptor wafer, but then a self-alignment mechanism controls a relative position between the die and the acceptor wafer during the bonding. This enhances bonding placement accuracy compared to existing die-to-wafer bonding tools, among other advantages.

Description

SYSTEM AND METHOD FOR DIE BONDING SELF-ALIGNMENTCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of EP application 24179463.5 which was filed on June 03, 2024. and EP application 24190100.8 which was filed on July 22, 2024 which are incorporated herein in its entirety by reference.TECHNICAL FIELD

[0001] The present disclosure relates generally to a method and tool for die bonding.BACKGROUND

[0002] In manufacturing processes of integrated circuits (ICs), multiple finished or unfinished ICs (e.g., whole wafers, diced wafers, partially diced wafers, chips, die, etc.) may be placed in contact, stacked, bonded, or otherwise joined (e.g., to heterogeneous or homogeneous devices) at various points in the fabrication process. Heterogeneous integration, e.g., the integration of different circuits or other patterned devices, may rely upon joining of specific portions (for example, conductive contact elements) of multiple die — where these specific portions may be aligned in three-dimensional space to ensure functional connectivity. Alignment of these die, which may have multiple fabrication layers, different critical dimensions, different nodes, packaging, etc., with each other may require different techniques than used for lithography during fabrication. As the physical sizes of IC components continue to shrink, and their structures continue to become more complex, accuracy and throughput in integration become more important. For applications such as heterogeneous integration, it may be desirable to obtain both accurate and fast placement of die with respect to one another. In the context of semiconductor manufacture, improvements in die placement and alignment (e.g., improvements in heterogeneous integration) lead to improvements in IC manufacturing and integration abilities.SUMMARY

[0003] According to an embodiment, there is provided a method for bonding semiconductor substrates, the method comprising: causing self-alignment to control a relative position between the semiconductor substrates during the bonding.

[0004] According to an embodiment, there is provided a system for bonding semiconductor substrates, the system comprising: a structure configured to cause self-alignment to control a relative position between the semiconductor substrates during the bonding.

[0005] In some embodiments, one of the semiconductor substrates comprises a semiconductor die,and another one of the semiconductor substrates comprises an acceptor location; and the structure causes self-alignment of the semiconductor die relative to the acceptor location during transfer of the semiconductor die to the acceptor location for bonding.

[0006] According to another embodiment, a non-transitory, machine-readable medium is provided having instructions thereon, the instructions when executed by a processor being configured to perform a method as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0008] Figure 1A is a schematic diagram illustrating an exemplary die bonding method, according to one or more embodiments.

[0009] Figure IB is another schematic diagram illustrating the exemplary die bonding method, according to one or more embodiments.

[0010] Figure 1C is another schematic diagram illustrating the exemplary die bonding method, according to one or more embodiments.

[0011] Figure ID is another schematic diagram illustrating the exemplary die bonding method, according to one or more embodiments.

[0012] Figure 2A is a schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0013] Figure 2B is another schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0014] Figure 2C is another schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0015] Figure 2D is another schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0016] Figure 2E is another schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0017] Figure 2F is another schematic diagram illustrating an example method of die placement, according to one or more embodiments.

[0018] Figure 3A is a schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0019] Figure 3B is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0020] Figure 3C is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0021] Figure 3D is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0022] Figure 3E is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0023] Figure 3F is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0024] Figure 3G is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0025] Figure 3H is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0026] Figure 31 is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0027] Figure 3J is another schematic diagram illustrating portions of an example system for die bonding, according to one or more embodiments.

[0028] Figure 4 illustrates another example embodiment of the system shown in Figure 3A-3 J, including a structure configured to cause self-alignment to control a relative position between semiconductor substrates (e.g., between a donor die and an acceptor substrate) during bonding, according to one or more embodiments.

[0029] Figure 5 illustrates several examples of possible first self-alignment patterns and corresponding second self-alignment patterns, according to one or more embodiments.

[0030] Figure 6 illustrates first and second self-alignment patterns that are electrostatically activated, according to one or more embodiments.

[0031] Figure 7 illustrates hydrophilic-hydrophobic self-alignment, according to one or more embodiments.

[0032] Figure 8 illustrates an example structure with a first self-alignment pattern comprising a donor mechanical structure, and a corresponding second self-alignment pattern comprising an acceptor mechanical structure, according to one or more embodiments.

[0033] Figure 9A is a schematic diagram illustrating an example method for die bonding with radiation mediated release, and self-alignment, according to one or more embodiments.

[0034] Figure 9B is another schematic diagram illustrating an example method for die bonding with radiation mediated release, and self-alignment, according to one or more embodiments.

[0035] Figure 9C is another schematic diagram illustrating an example method for die bonding with radiation mediated release, and self-alignment, according to one or more embodiments.

[0036] Figure 9D is another schematic diagram illustrating an example method for die bonding with radiation mediated release, and self-alignment, according to one or more embodiments.

[0037] Figure 10A is a schematic diagram illustrating an example method for die bonding with radiation mediated release and a flexible interposer layer, along with self-alignment, according to one or more embodiments.

[0038] Figure 10B is another schematic diagram illustrating an example method for die bonding with radiation mediated release and a flexible interposer layer, along with self-alignment, according to one or more embodiments.

[0039] Figure 10C is another schematic diagram illustrating an example method for die bonding with radiation mediated release and a flexible interposer layer, along with self-alignment, according to one or more embodiments.

[0040] Figure 10D is another schematic diagram illustrating an example method for die bonding with radiation mediated release and a flexible interposer layer, along with self-alignment, according to one or more embodiments.

[0041] Figure 11 is a flowchart which illustrates an exemplary method of donor die (self) alignment and placement, according to one or more embodiments.

[0042] Figure 12 is a block diagram of an example computer system, according to one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0043] Embodiments of the present disclosure are described in detail with reference to the drawings, which are provided as illustrative examples of the disclosure so as to enable those skilled in the art to practice the disclosure. Notably, the figures and examples below are not meant to limit the scope of the present disclosure to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present disclosure can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present disclosure will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the disclosure. Embodiments described as being implemented in software should not be limited thereto, but can include embodiments implemented in hardware, or combinations of software and hardware, and vice-versa, as will be apparent to those skilled in the art, unless otherwise specified herein. In the present specification, an embodiment showing a singular component should not be considered limiting; rather, the disclosure is intended to encompass other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present disclosure encompasses present and future known equivalents to the known components referred to herein by way of illustration.

[0044] Although specific reference may be made in this text to the manufacture of ICs, it should beexplicitly understood that the description herein has many other possible applications. For example, it may be employed in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal display panels, thin-fdm magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” in this text should be considered as interchangeable with the more general terms “substrate” and “target portion”, respectively. The term “wafer” may be used generally to refer to a large unit of manufacture (which may be the largest unit of manufacture), while the term “die” may be used to refer to a smaller unit of manufacture which may correspond to a lithography pattern, a portion of a lithography pattern, multiple lithography patterns, etc. A “die” may correspond to a portion of “wafer” — that is a “die” may be produced by dicing or otherwise dividing a “wafer”. The term “die” should be considered as interchangeable with the term chip, chiplet, or other terms for IC divisions. A patterning device (for example, a lithography device) can comprise, or can form, one or more patterns, which may correspond to one or more die. The patterns can be generated utilizing CAD (computer-aided design) programs, based on a pattern or design layout, this process often being referred to as EDA (electronic design automation). As used throughout this application “or”, unless indicated otherwise, takes a non-exclusive meaning, e.g., encompassing both “and” and “or”. “Each”, “every”, “all”, “corresponding”, “individual” and other relational terms encompass substantially “each”, “every”, “all”, etc., including cases in which each, every, all, corresponding, individual, etc. may include relationship which are not one-to-one, or do not include every possible item. For example, every may exclude items, such as items determined to be defective during testing. Each may exclude items, such as edge items, which are not used. All may exclude items, such as excess items. Corresponding may not require that items correspond in an exactly one to one manner. For example, a first item may correspond to two of a second item or vice versa. In some cases, individual may refer to multiple of an item, such as each item A has individual item B, where an item A may have two of an item B.

[0045] Reference is now made to Figures 1A-1D, which are schematic diagrams illustrating an exemplary die bonding method consistent with embodiments of the present disclosure. The exemplary die bonding method is depicted in relation to a reference set of axes, which are consistent through the schematic illustrations. The reference axes are provided for ease of description only and are not to be taken as limiting. Included methods and apparatuses may instead be described with reference to a different set of axes (e.g., cylindrical coordinates, polar coordinates, etc.), a different origin point (e.g., an origin point in the donor die, an origin point in an acceptor, origin point in between the donor die and acceptor, etc.), or a different orientation. The reference set of axes is chosen such that the fabrication plane of the die (i.e., a substrate surface) lies in the x-y plane and where the fabrication direction is parallel or antiparallel to the z-axis for both the donor die and acceptor locations.

[0046] As shown in Figures 1A-1D, the exemplary die bonding method may involve a donor die 102 and an acceptor die 104 (or more generally an acceptor location). Herein, the term “donor” and theterm “acceptor” are used for ease of description. It should be understood that the term “donor” and the term “acceptor” are provided for reference and are relative descriptions, and that elements described as corresponding to a “donor” can instead correspond to an “acceptor” and vice versa. Further, while just one donor die and acceptor die are depicted in Figure 1A, it will be appreciated that there may be multiple such die and that multiple donor die may be essentially simultaneously bonded with multiple acceptor locations, e.g., die where, for example, multiple die are still part of (all or part) a substrate in or on which they are formed.

[0047] The donor die 102 may have one or more electrically active areas 106 or other features on an alignment face of the donor die 102. The one or more electrically active areas may be conductive, formed from a material such as metal. The one or more electrically active areas may correspond to one or more vias (e.g., one or more through silicon vias (TSVs)), one or more electrical contact lines, one or more contact pads, one or more packaging pads, or other one or more electrically conductive areas.

[0048] The donor die 102 may have one or more electrically inert areas (for example, an electrically insulating area) outside of the one or more electrically active areas 106, such as on the alignment face of the donor die 102. The one or more electrically active areas 106 may be recessed (as shown) with respect to one or more other surfaces of the donor die 102. The one or more electrically active areas 106 may correspond to one or more contacts (e.g., to source, to drain, to gate, etc.) to one or more electrical devices within the donor die 102 (not shown). The acceptor die 104, likewise, may have one or more electrically active areas 108, which may have one or more similar properties to the one or more electrically active areas 106.

[0049] The donor die 102 may also or instead have one or more doped areas 110, such as on an alignment face of the donor die 102, recessed below the alignment face of the donor die 102, etc. While the term “doped” is used, it should be understood that the one or more doped areas 110 may be any areas which, through the course of fabrication, come to have one or more different electrical characteristics than the bulk of the substrate (e.g., silicon wafer). The one or more doped areas 110 may correspond to source, drain, gate, ground, or other areas of a circuit which is doped or otherwise altered (e.g., through implantation, oxide growth, thin film deposition, etc.) to have a different electrical characteristic than the bulk of the substrate. The one or more doped areas 110 may include one or more conductive layers (e.g., one or more highly doped or electrically conductive layers) or one or more insulative layers (e.g., one or more oxide layers). The donor die 102 may have one or more undoped areas (for example, an area where the substrate retains the characteristic of the bulk substrate) outside of the one or more doped areas 110, such as on the alignment face of the donor die 102. The one or more doped areas 110 may be recessed, buried, coplanar (as shown), etc. with respect to one or more other surfaces of the donor die 102. The one or more doped areas 110 may correspond to one or more regions (e.g., to one or more source regions, one or more drain regions, one or more gate regions, one or more dielectric regions, etc.) of one or more electrical devices within the donordie 102 or one or more regions which may form one or more electrical devices across both the donor die 102 and the acceptor die 104 once those die are bonded. The acceptor die 104, likewise, may have one or more doped areas 112, which may have one or more similar properties to the one or more doped areas 110.

[0050] As shown in Figures 1A and IB, the exemplary die bonding method may involve alignment of at least one of the electrically active areas 106 or doped areas 110 of the donor die 102 with at least one of the electrically active areas 108 or doped areas 112 of the acceptor die 104. The exemplary die bonding method may involve bringing the donor die 102 into contact with the acceptor die 104 while maintaining alignment between, e.g., one or more electrically active areas 106 and one or more electrically active areas 108 so that the one or more electrically active areas 106 and the one or more electrically active areas 108 may be joined for cross-die electrical communication. The exemplary die bonding method may involve aligning one or more doped areas 110 of the donor die 102 with one or more doped areas 112 of the acceptor die 104. Aligning may encompass bringing into contact, aligning one or more edges of various regions, having overlap, having non-overlap, or any other appropriate alignment scheme. The exemplary die bonding method may involve applying or maintaining pressure between the donor die 102 and the acceptor die 104, while bonding occurs between the donor die 102 and the acceptor die 104. The donor die 102 may be supported by a carrier 114, which may be a substrate which is transparent to a range of radiation (e.g., infrared radiation, a portion of the optical spectrum, etc.). The acceptor die 104 may likewise be supported by a carrier 116, which may or may not be transparent to a range of radiation. The alignment may be complicated by the multiple layers of the donor die 102 or the multiple layers of the acceptor die 104, which may be optically opaque.

[0051] Figures 1A and IB depict a cross-sectional view of portions of the exemplary die bonding method showing relative positioning between the donor die 102 and the acceptor die 104 (e.g., an acceptor location). As shown in Figure 1A, the donor die 102 and the acceptor die 104 may be brought together along the z-axis, while the position of the donor die 102 or the acceptor die 104 may be adjusted in the x-y plane (e.g., perpendicular to the z-axis of approach), such as to improve alignment between the donor die 102 and the acceptor die 104. As shown in Figure IB, alignment can be achieved between, e.g., one or more electrically active areas 106 and one or more electrically active areas 108 or between one or more doped areas 110 of the donor die 102 with one or more doped areas 112 of the acceptor die 104.

[0052] Once aligned, the donor die 102 and the acceptor die 104 are bonded together. In an embodiment, the bonding is a direct or fusion bonding (e.g., involving van der Waals forces). In an embodiment, the bonding is an intermolecular bonding, e.g., van der Waals bonding. In an embodiment, the bonding may include covalent, ionic, or metallic (e.g., chemical) bonding, e.g., hydrogen bonding. In an embodiment, the bonding is aided by a material (e.g., a suitable bonding or adhesive material) applied to an alignment surface of the donor die 102 or acceptor die 104 orprovided to a gap between the donor die 102 and the acceptor die 104 (e.g., in the form of gas or liquid). In some embodiments, physical contact between the donor die 102 and the acceptor die 104 may include bonding, such as through a bonding wavefront generated by contact (or atomic level proximity), such as of a surface prepared for hydrogen bonding.

[0053] As shown in Figure IB, the donor die 102 and the acceptor die 104 may be annealed after contact as depicted by the wavy lines (while wavy lines are shown here at both the donor die 102 and the acceptor die 104, the annealing agent need not be provided at both the donor die 102 and the acceptor die 102 nor needs to be applied in the direction(s) shown). Annealing may be or include heat annealing, electrical annealing, electrostatic processes, etc. In some embodiments, annealing may include annealing of in-plane (or prominent) regions that are bonded or annealing of one or more recessed areas which may increase the volume of fill in a recess area (such as through thermal expansion, capillary force, etc.) and may cause physical contact and bonding of areas previously not in contact. As shown in Figure 1C, annealing may cause physical or chemical changes, such as in the one or more electrically active areas 106 of the donor die 102 or in the one or more electrically active areas 108 of the acceptor die 104, which may cause or improve physical contact or electrical contact between an electrically active area 106 and an electrically active area 108. Annealing may therefore produce or enhance electrical connectivity between elements of the donor die 102 and the acceptor die 104 (e.g., integration). This electrical connectivity may occur even if an electrically active area 106 and an electrically active area 108 differ — for example, have different recessed depths, are made up of different materials, have different dimensions, etc. In an embodiment, the prior bonding described with respect to Figure 1 A may be temporary during one or more portions of the annealing process, wherein the annealing process forms tight connections between donor die 102 and the acceptor die 104. In an embodiment, the annealing may occur in the system where the bonding occurs. In an embodiment, the annealing may occur in a separate system from the system in which the bonding occurs, e.g., the donor and acceptor dies are transported out of the bonding system into an annealing system which can include one or more heating elements (e.g., one or more electrical heating elements, one or more elements to provide radiation heating, etc.) to provide the heat for the annealing.

[0054] Once the donor die 102 and the acceptor die 104 are bonded, the carrier 114 may be removed as shown in Figure IB. Additionally or alternatively, the carrier 116 may be removed then as well. Alternatively, once the donor die 102 and the acceptor die 104 are annealed, the carrier 116 may be removed as shown in Figure 1C. Additionally or alternatively, the carrier 114 may be removed then as well.

[0055] Figure ID depicts a plan view of an example die bonding method according to this disclosure. As shown in Figure ID, the donor die 102 or the acceptor die 104 (e.g., an acceptor location) may have one or more die alignment marks along the x-y plane to facilitate alignment of the die as a whole. Alignment marks in the x-y plane of a die (e.g., one or more die (alignment) marks 120 on the donor die 102 or one or more die (alignment) marks 122 on the acceptor die 104) may reduce the areaavailable for circuitry. One or more alignment marks may be placed in a waste area, such as an area between chips, which may then be destroyed (e.g., removed) during dicing. Dicing herein refers to mechanical separation of areas of a substrate (e.g., a unit of manufacture) into smaller areas (e.g., dies or chips) which may contain one or more units of operation (e.g., a logic device, a memory unit, etc.). Dicing may operate using any appropriate method — for example, scribing and breaking, mechanical sawing, laser cutting, etc. — and may destroy (e.g., grind to powder or otherwise render inoperable for circuitry placement) a non-zero linewidth portion of the substrate volume when separating die. Alignment marks may be additively or subtractively fabricated, such as by etching or deposition in the z-direction. Alignment marks 120 and 122 may be the same or different. Alignment marks 120 and 122 may be a multi-directional alignment mark, i.e., capable of determining alignment in more than one direction, such as a bi-direction alignment mark, an example of which is shown as mark 120 in Figure ID. The alignment mark 120 or alignment mark 122 may be a fine alignment mark, such as for alignment in the pm scale. The alignment mark 120 may be located on the donor die 102 while the acceptor die 104 may have an alignment mark 122 located in a waste area, or vice versa. Alternatively or additionally, one or more electrically active or doped areas of the donor die 102 or one or more electrically active or doped areas of the acceptor die 104 (not shown in Figure ID) or other surface features may function as a reference for alignment (e.g., an alignment mark) of the donor die 102 or the acceptor die 104.

[0056] The donor die 102 and the acceptor die 104 may be aligned in up to three dimensions before or during contact between the donor die 102 and the acceptor die 104. For example, the donor die 102 or the acceptor die 104 may be positioned in the x-y plane as the donor die 102 in the acceptor die 104 are contacted. The donor die 102 or the acceptor die 104 may be positioned by operation of a die actuator or other die-scale elements, such as by piezoelectric stepper elements, or by operation of a chuck or other carrier structure -scale elements, such as by a motor or other actuator. The position of the donor die 102 or the acceptor die 104 may be adjusted with respect to up to six degrees of freedom. For example, given an origin point at a central part of the donor die 102, the donor die 102 may be positioned by movement along the X axis (e.g., in a positive or negative X direction), along the y-axis (e.g. in a positive or negative Y direction), along the z-axis (e.g., in a positive or negative Z direction). The donor die 102 may also be positioned rotationally with respect to each of those axes — e.g., rotated with respect to the x-axis, rotated with respect to the y-axis, rotated with respect to the z- axis. That is, the donor die 102 may be positioned by free movement in space accounted for by six different types of movement (where the movements listed above are provided as examples but where the movements may be described by other axes). Of course, the acceptor die 104 may be positioned alone or combined with positioning of the donor die 102. Positioning or adjustment of position herein, unless the context otherwise requires, includes displacement, rotation or any combination thereof.

[0057] In some embodiments, the donor die 102 and the acceptor die 104 may be measured with respect to a reference plane or structure (e.g., the X-Y plane), including with respect to the samereference plane or structure, but the donor die 102 or the acceptor die 104 may be flipped (before or after measurement) so that the fabrication surface of the donor die 102 and the fabrication surface of the acceptor die 104 may be bonded (see, e.g., the bottom diagram of Figure ID). The one or more alignment marks (e.g., the alignment marks 120 and 122) may be on the fabrication surface of the donor die 102 and the acceptor die 104, respectively. Once the donor die 102 or the acceptor die 104 is flipped, one or more alignment mark may be rendered invisible (such as due to opacity of a die) to an alignment measurement tool. The alignment of the flipped die may therefore be performed based on previously measured positions of the die (e.g., of the one or more alignment marks of the die) with respect to a structure, such as the donor die 102 with respect to carrier 114 or such as the acceptor die 104 with respect to the carrier 116.

[0058] Figures 2A-2F are schematic diagrams illustrating an example method of die placement. Figures 2A-2F are described with reference to “donor” (e.g., a “donor die”, a “donor substrate” comprising multiple “donor die”, or a “donor location” as a general term for any of these) and “acceptor” (e.g., an “acceptor die”, “acceptor substrate” comprising multiple “acceptor die”, or an “acceptor location”), which are relative descriptors and donor die may instead be acceptor die and vice versa. Figures 2A-2F are described with respect to donor die and acceptor die; but may instead be a donor substrate or acceptor substrate, where a “substrate” may comprise multiple “die”, including un-diced (e.g., unseparated) die in the form of all or part of a semiconductor wafer; or more generally a “donor” or “acceptor” location or other feature. Figure 2A-2F are cross-sectional views of die placement of donor dies (e.g., donor die 202A, 202B, 202C) on acceptor dies (e.g., acceptor die 204A and acceptor die 204B). In some embodiments, multiple steps which are depicted as occurring substantially simultaneously in Figures 2A-2F may be performed sequentially. In some embodiments, multiple steps which are depicted as occurring sequentially in Figures 2A-2F may be performed substantially simultaneously. In some embodiments, multiple donor dies may be aligned or placed on their respective acceptor dies substantially simultaneously, including donor dies which are proximate (including adjacent) or distant (e.g., non-adjacent but within the same acceptor substrate). In some embodiments, steps may be performed in a different order.

[0059] Figure 2A is a cross-sectional view of donor dies 202A-202C which are to be placed on acceptor dies 204A-204B (e.g., acceptor locations). The donor dies 202A-202C are supported by a carrier 214. The donor dies 202A-202C may be adhered to the carrier 214 in any appropriate manner, such as by vacuum adhesion, electrostatic adhesion, intermolecular adhesion, van der Waals adhesion, mechanical interlocking, surface reaction, static friction, gravitational force, etc. The donor dies 202A-202C may be adhered to the carrier 214 by use of, for example, an adhesive (e.g., glue), such as an organic, polymer glue. The carrier 214 may be a transparent substrate, such as glass, sapphire, polymer, etc. substrate. The donor dies 202A-202C may be placed on the carrier 214 by any appropriate method, such as by a pick and place tool. The carrier 214 may be supported by a chuck or any other appropriate support structure.

[0060] The acceptor dies 204A-204B (e.g., acceptor locations) are supported by a support structure 216. In an embodiment, the acceptor dies 204A-204B may be part of an undiced or partially diced acceptor wafer. The acceptor dies 204A-204B may be adhered to the support structure 216 in any appropriate manner, such as by vacuum adhesion, electrostatic adhesion, intermolecular adhesion, mechanical interlocking, surface reaction, static friction, gravitational force, etc. The acceptor dies 204A-204B may be adhered to the support structure 216 by use of, for example, an adhesive (e.g., glue), such as an organic, polymer glue. In an embodiment, where, for example, the acceptor dies 204A-204B are diced die, the support structure may be a carrier (e.g., like carrier 214) and may be a transparent substrate, such as glass, sapphire, polymer, etc. substrate. The acceptor dies 204A-204B may be placed on the support structure 216 by any appropriate method, such as by a pick and place tool. The support structure 216 may be, or may be supported by, a chuck or any other appropriate structure.

[0061] The donor dies 202A-202C and the acceptor dies 204A-204B may be aligned with one another at alignment points 203A and 205A (for donor die 202A and acceptor die 204A), alignment points 203B and 205B (for donor die 202B and acceptor die 204B), and alignment points 203C and 205 C (for donor die 202C and acceptor die 204B). In some embodiments, multiple donor die may be placed on a single acceptor die, and vice versa, such as depending on integration goals. The alignment points 203A-203C are depicted for the donor dies 202A-202C, while the alignment points 205A-205C are depicted for the acceptor dies 204A-204B. These alignment points are provided for ease of description only and need not be physical features. There may be multiple alignment points per die. The alignment points may be alignment marks (for example, the alignment marks of Figure ID), die edges, die comers, other features on edges or surfaces of die, a substrate, or other structures. The alignment points may be used to align donor and acceptor die or other substrates, such as by measurement of the locations of various alignment points and then adjustment of the position of the donor or acceptor die, such as by movement of a carrier supporting the die, to align an alignment point of the donor die with an alignment point of the acceptor die (or vice versa). The alignment points may be aligned directly to one another (e.g., as depicted in Figures 2A-2F). In some embodiments, the alignment points may be aligned relative to one another (e.g., in a predetermined relationship, such as separated by a vector), such as depicted in the bottom of Figure ID, where the alignment marks are non-overlapping.

[0062] In Figure 2A, the carrier 214 (or the support structure 216 which forms a carrier) may be positioned, such as in the X-Y plane, in order to align the alignment point 203A of the donor die 202A with the alignment point 205A of the acceptor die 204A.

[0063] In Figure 2B, the donor die 202A may be released from the carrier 214 by any appropriate mechanism, such as release mechanism 230A. The donor die 202A meets the acceptor die 204A (e.g., an acceptor location) at alignment point 207A. The release of the donor die 202A may be facilitated by gravity, by electrostatic forces, by physical forces, radiation mediated release, etc. The alignmentof the donor die 202A and the acceptor die 204A at the alignment point 207A (which represents a combination of the alignment point 203 A and the alignment point 205 A of Figure 2A) may be assisted by any appropriate alignment mechanism, including self-alignment (e.g., attraction of one area of the donor die 202A to a corresponding area of the acceptor die 204A). In an embodiment, the release occurs while donor die 202A is in (at least partial) contact with acceptor die 204A. In an embodiment, the release occurs before donor die 202A is in contact with the acceptor die 204A.

[0064] In Figure 2C, the carrier 214 (and alternately or additionally the support structure 216 which forms a carrier) may be moved to bring another donor die (e.g., the donor die 202C) into alignment with another acceptor die or location (e.g., the acceptor die 204B). The alignment of alignment point 203 C (of donor die 202C) and alignment point 205 C (of acceptor die 204B) may be based on measurements of the relative positions of the alignment points (such as using an alignment mark or feature on a die or carrier structure, using a position of an alignment point on another donor or acceptor die, etc.). The alignment of alignment point 203C (of donor die 202C) and alignment point 205 C (of acceptor die 204B) may be based on one or more substantially simultaneous measurement of the relative positions of an alignment point, such as using an alignment mark or feature of a die or carrier structure, using an alignment target or feature of another donor or acceptor die, etc. Although alignment of only one donor die (e.g., the donor die 202C) and acceptor die (e.g., the acceptor die 204B) is depicted, alignment of one or more sets of donor and acceptor dies or substrates may occur substantially simultaneously, such as if for a given relative position of the carrier 214 and the support structure 216 the alignment points of multiple donor dies are aligned with the alignment points of multiple acceptor dies. However, the ability to place multiple donor dies substantially simultaneously may depend on the placement of the donor dies on the carrier 214 and the ability of the release mechanism to release multiple donor dies.

[0065] In Figure 2D, the donor die 202C may be released from the carrier 214 by any appropriate mechanism, such as release mechanism 230C. The donor die 202C meets the acceptor die 204B at alignment point 207C. The release of the donor die 202C may be facilitated by gravity, by electrostatic forces, by physical forces, radiation mediated release, etc. The alignment of the donor die 202C and the acceptor die 204B (e.g., an acceptor location) at the alignment point 207C (which represents a combination of the alignment point 203 C and the alignment point 205 C of Figure 2A) may be assisted by any appropriate alignment mechanism, including self-alignment. In an embodiment, the release occurs while donor die 202B is in (at least partial) contact with acceptor die 204B. In an embodiment, the release occurs before donor die 202B is in contact with the acceptor die 204B.

[0066] In Figure 2E, the carrier 214 (and alternately or additionally the support structure 216 which forms a carrier) may be moved to bring another donor die (e.g., the donor die 202B) into alignment with another acceptor die (e.g., the acceptor die 204B). The alignment of alignment point 203B (of donor die 202B) and alignment point 205B (of acceptor die 204B) may be based on previousmeasurements of the relative positions of the alignment points (such as using an alignment mark on a die or carrier structure, using an alignment point on another donor or acceptor die, etc.). The alignment of alignment point 203B (of donor die 202B) and alignment point 205B (of acceptor die 204B) may be based on one or more substantially simultaneous measurement of the relative positions of an alignment point, such as using an alignment mark or feature of a die or carrier structure, using an alignment target or feature of another donor or acceptor die, etc. As depicted, the donor die 202B and the donor die 202C are aligned to the same acceptor die (e.g., the acceptor die 204B). In some embodiments, the donor die are placed on the acceptor die in a substantially one-to-one relationship (e.g., as depicted for the donor die 202A and the acceptor die 204A). In some embodiments, multiple donor die (or acceptor die) may be placed on the same acceptor die (or donor die). In some embodiments, multiple donor die (or acceptor die) may be placed on un-diced (e.g., unseparated) acceptor die (or donor die), such as all or part of a substrate containing acceptor die (or donor die). In some embodiments, a donor die may be placed on a acceptor die that has multiple die, including stacked (e.g., bonded) die, such as in a three layer die bonding stack.

[0067] In Figure 2F, the donor die 202B may be released from the carrier 214 by any appropriate mechanism, such as release mechanism 23 OB. The donor die 202B meets the acceptor die 204B at alignment point 207B. The release of the donor die 202B may be facilitated by gravity, by electrostatic forces, by physical forces, radiation mediated release, etc. The alignment of the donor die 202B and the acceptor die 204B at the alignment point 207B (which represents a combination of the alignment point 203B and the alignment point 205B of Figure 2A) may be assisted by any appropriate alignment mechanism, including self-alignment. In an embodiment, the release occurs while donor die 202B is in (at least partial) contact with acceptor die 204B. In an embodiment, the release occurs before donor die 202B is in contact with the acceptor die 204B.

[0068] Figures 3A-3J are schematic diagrams illustrating portions of an example system 301 for die bonding. Figures 3A-3J are described with reference to “donor” (e.g., a donor substrate or wafer, a donor die, etc.) and “acceptor” (e.g., an acceptor location, an acceptor substrate or wafer, an acceptor die, etc.), which are relative descriptors as used herein and donor may instead be acceptor and vice versa. Each of Figures 3A, 3C, 3E, 3G, and 31 is a plane view of the system 301 during placement of donor die on an acceptor die (e.g., an acceptor location). Each of Figures 3B, 3D, 3F, 3H, and 3J is a cross-sectional view of the system 301 during placement of donor die on the acceptor die. The views of the system 301 in various figures represent different operations of the system 301, but operations depicted as occurring in different figures may occur at different times or may instead be performed simultaneously and operations depicted as occurring in the same figure may instead be performed individually or at different times. A donor substrate 300 and an acceptor substrate 350 are depicted as circular, but may instead be any appropriate shape, including rectangular, square, etc. The donor substrate 300 (and acceptor substrate 350) may be the substrate in or on which the donor die (or acceptor die) have been formed. The donor substrate 300 (or acceptor substrate 350) may be a“reconstructed wafer”, in which donor die (acceptor die) (or other disparate portions of a semiconductor substrate) are arranged or supported on a carrier, e.g., to be in position suitable for die bonding. So, the donor substrate 300 (acceptor substrate 350) may be a carrier and donor die (acceptor die), where the donor die (acceptor die) may be held (e.g., adhered) to the carrier by any appropriate method, such as by gravitational force, by adhesive (e.g., organic, polymer adhesive), by electrostatic forces, etc. The donor substrate 300 (acceptor substrate 350) may contain previously tested donor die (acceptor die), such as donor die (acceptor die) that passed a failure analysis or other post fabrication testing. The donor substrate 300 (acceptor substrate 350) may contain donor die (acceptor die) from the same or different semiconductor substrates (e.g., fabrication substrates), including donor die (acceptor die) of different types, different dimensions, etc. The donor substrate 300 (acceptor substrate 350) may have donor die (acceptor die) placed on the donor substrate 300 (acceptor substrate 350) by any appropriate method, such as a pick and place tool. The donor substrate 300 (acceptor substrate 350) may be supported, such as by a carrier structure, vacuum chuck, electrostatic chuck, etc., by either a top side (e.g., fabrication face) or backside (e.g., bulk substrate or carrier structure face) or by different faces at various points. The donor substrate 300 or donor die (acceptor substrate 350 or acceptor die) may have fabricated devices on multiple faces, such as through silicon vias (TSVs), contact pads, etc., such that both atop side and backside are fabrication faces.

[0069] In Figure 3A, the donor substrate 300 may be placed on a substrate chuck 320A. The substrate chuck 320A may be an appropriate substrate chuck, such as to support the donor substrate 300 in the form of a semiconductor substrate or a carrier of the donor substrate 300. The substrate chuck 320A may be supported by a support structure 322A. The support structure 322A may be a moveable support structure, which may move in the X-Y plane, such as from a first position where the substrate chuck 320A receives the donor substrate 300 to a second position where the donor substrate 300 may be subjected to metrology. The substrate chuck 320A may comprise (e.g., support) one or more die actuators or other mechanical or electrical actuators which may move a donor die or the donor substrate 300 in one or more dimensions, including in the X-Y plane, in the Z-direction, rotationally, etc. The substrate chuck 320A may have one or more alignment marks, such as to allow a camera or other measurement system to track the position of the substrate chuck 320A. The substrate chuck 320A may have multiple sets of alignment marks, such as coarse alignment marks or fine alignment marks. The substrate chuck 320A may move, such as by action of the support structure 322A, from one position to another, in free space, etc. The support structure 322A may be configured to move in multiple directions and in multiple scales (e.g., in a coarse step and a fine step), such as by multiple motors or steppers. The support structure 322A may be activated by a controller of the example system 301 — where the controller or processor system of the example system 301 (not depicted in Figures 3A - 3J, but which may be formed by or included in the computer system CS shown in Figure 12 and described below) may also control the placement of the donor substrate 300 on the substrate chuck 320A and other operations described herein.

[0070] The substrate chuck 320A may have a measurement point (or alignment point), such as identified by a cruciform measurement mark 327 and a round zero measurement mark 328, which are provided merely as examples and where any appropriate zero measurement mark may be used. The measurement point may be used to place the donor substrate 300 on the substrate chuck 320A, such as during movement of the substrate onto the chuck (for example, by insertion of the donor substrate by a substrate handler). The measurement point may be used to measure relative positions of the donor die of the donor substrate 300 once the donor substrate 300 is placed on the substrate chuck 320A. The placement of the donor die may be measured, such as with up to nm precision, with respect to the measurement point. The measurement of the position of the donor die after their placement may be obtained from any appropriate measurement system, such as optical microscopy, reflectometry, etc.

[0071] Figure 3A also depicts a further substrate chuck 320B on a support structure 322B. The substrate chuck 320B may be any appropriate substrate chuck, such as substantially identical to the substrate chuck 320A. The support structure 322B may be any appropriate support structure, such as substantially identical to the support structure 322A. In some embodiments, the substrate chuck 320B and the substrate chuck 320A may be substantially indistinguishable. In some embodiments, the support structure 322B and the support structure 322A may be substantially indistinguishable. Although two substrate chucks and two support structures are depicted, in some embodiments more or less substrate chucks and support structures may be present in the system 301. Operations depicted as performed by the substrate chuck 320B (substrate chuck 320A) may instead or additionally be performed by any appropriate substrate chuck. Likewise, operations depicted as performed by the support structure 322B (support structure 322A) may instead or additionally be performed by any appropriate support structure.

[0072] Figure 3A also depicts flipper 330. The flipper 330 may be any appropriate apparatus in system 301 which may flip a substrate (e.g., donor substrate 300), such as about the longitudinal axis or plane of the donor substrate 300 depicted in Figure 3A. The flipper 330 will be described in more detail in reference to Figures 3E and 3F.

[0073] In Figure 3B, a cross-sectional view of a donor substrate 300 is depicted. The donor substrate 300 comprises a carrier 314 which supports one or more donor die (e.g., donor die 302A-302C). The substrate may have one or more alignment points, such as alignment point 315, used to measure a relative position of the donor die 302A-302C with respect to the carrier. The donor die may have alignment points, such as alignment points 303A-303C for donor die 302A-302C, respectively. The alignment points are provided as schematic representations in these drawings for ease of description, and may be any appropriate alignment points, including alignment marks, fabricated features, edge features, etc., as previously described. While the donor substrate 300 is on a substrate chuck (e.g., the substrate chuck 320A of Figure 3A), the positions of the donor die (e.g., the donor die 302A-302C) are measured, such as by metrology tool 340A. The positions may be measured as absolute positions, relative positions, positions relative to other die, positions relative to an alignment point of thesubstrate, etc. The measured positions may be stored by a controller (or sensor system, which may be formed by or included in the computer system shown in Figure 12 and described below) of the system 301, such as for later positioning of the donor substrate 300. The metrology tool 340A may include an optical sensor such as a camera, including a still camera, a video camera, etc., or other optical sensors. The metrology tool 340A may include a capacitive sensor or other sensors. The metrology tool 340A may be any appropriate tool for measurement of a position of a donor die, measurement of a position of an alignment point of the donor die, measurement of a position of alignment mark of the donor die, etc.

[0074] In Figure 3C, the donor substrate 300 is supported by the substrate chuck 320A, which is supported by the support structure 322A. Once the position of the donor dies are measured, the substrate chuck 320A may be moved, such as out of the measurement position. The support structure 322A may move (e.g., along direction 324) to the position of the support structure 322B, while the support structure 322B may move (e.g., along direction 323) to the position of the support structure 322A. The positions are provided as examples, and the support structures may move to different positions. For example, in some embodiments, the support structure 322B may move to a loading position, such as to receive an acceptor substrate (e.g., the acceptor substrate 350). The substrate chuck 320A may then occupy another position in the system 301 (e.g., a bonding position, a flipping position, etc.). The position the substrate chuck 320A moves to after measurement of the positions of the donor die (e.g., after the measurement depicted in Figure 3B) may be configured to allow the flipper 330 to accept the donor substrate 300 from the substrate chuck 320A.

[0075] In Figure 3D, the movement of the donor substrate 300 to a position other than the measurement position of Figure 3B is depicted. The movement may correspond to the movement of the donor substrate 300 in the direction 324, such as by movement of the support structure 322A, of Figure 3C. This figure is provided to show continuity of the die bonding process in both plane and cross-sectional views, but may occur substantially simultaneously with the process depicted in Figure 3C or Figure 3E, where, as previously described, steps which are depicted as occurring separately, including sequentially, may be performed substantially simultaneously.

[0076] In Figure 3E, the acceptor substrate 350 may be placed on a substrate chuck 320B. The substrate chuck 320B may be an appropriate substrate chuck, as previously described. The substrate chuck may be supported by a support structure 322B, which may be any appropriate support structure, as previously described.

[0077] In Figure 3E, the donor substrate 300 may be transferred to the flipper 330. The flipper 330 may accept (e.g., take) the donor substrate from the substrate chuck 320A, such as by use of edge clamps, vacuum clamps, finger prongs, etc. The flipper 330 may hold the donor substrate by one or more edges (e.g., one or more edges of the carrier 314) or one or more sides (for example, a backside of the carrier 314 which does not support the donor die). The flipper 330 may rotate the donor substrate 300 upside down (e.g., with respect to the direction of the gravitational force). The flipper330 may hold the donor substrate 300 upside down (e.g., opposite to) with respect to the X-Y plane which it previously occupied — or in any other appropriate direction. The flipper 330 may hold the donor substrate 300 or place the donor substrate 300 into a support structure, such that the donor substrate 300 faces the plane of the acceptor substrate 350. The flipper 330 may rotate or displace the donor substrate 300 in the X-Y plane, as well as displace or rotate the donor substrate 300 out of the X-Y plane. The flipper 330 may be any appropriate rotational or translational apparatus in the system 301.

[0078] In Figure 3F, a cross-sectional view of the acceptor substrate 350 is depicted. The acceptor substrate 350 comprises a carrier 316 which supports one or more acceptor dies (e.g., acceptor die 304A-304C). The substrate may have one or more alignment points, such as alignment point 317. The acceptor die may have alignment points, such as alignment points 305A-305C for acceptor die 304A- 304C, respectively. The alignment points are provided as schematic representations in these drawings for ease of description, and may be any appropriate alignment points, including alignment marks, fabricated features, edge features, etc., as previously described. While the acceptor substrate 350 is on the substrate chuck (e.g., the substrate chuck 320B of Figure 3E), the positions of the one or more acceptor dies (e.g., the acceptor die 304A-304C) are measured, such as by metrology tool 340B. The metrology tool 340B may be the same as the metrology tool 340A used to measure the positions of the one or more donor dies (e.g., the donor die 302A-302C of Figure 3B) or a different metrology tool. The metrology tool 340B may measure a different number of positions, substantially different positions (e.g., arranged differently on the acceptor substrate 300 than the positions on the donor substrate 300 as measured by the metrology tool 340A), different positions relative to dies (e.g., the donor die 302A-302C versus the acceptor die 304A-304C), etc. than the metrology tool 340A. The positions may be measured as absolute positions, relative positions, positions relative to other die, positions relative to an alignment point of the substrate, etc. The measured positions may be stored by a controller (or sensor system, which may be formed by or included in the computer system shown in Figure 12 and described below) of the system 301, such as for later positioning of the acceptor substrate 350. The metrology tool 340B may include an optical sensor such as a camera, including a still camera, a video camera, etc., or other optical sensors. The metrology tool 340B may include a capacitive sensor or other sensors. The metrology tool 340B may be any appropriate tool for measurement of a position of a donor die, measurement of a position of an alignment point of the donor die, measurement of a position of alignment mark of the donor die, etc. The acceptor substrate 350 may experience deformation due to the holding by a substrate chuck, etc. The metrology tool 340B may also enable determination of deformation of the acceptor substrate by measuring locations. A controller may determine the deformation of the acceptor substrate 350 based on those measured locations (e.g., from curve fitting, using a physical deformation model, etc.).

[0079] In Figure 3F, the donor substrate 300 is supported by a bonding support structure 332. The bonding support structure 332 may be part of the flipper 330 (of Figure 3E) or the donor substrate 300may be placed into the bonding support structure 332 by the flipper 330. The bonding support structure 332 may hold the donor substrate 300 opposite to a plane of the acceptor substrate 350. The bonding support structure 332 may hold the donor substrate by the carrier 314, including by one or more edges of the carrier 314. While in the bonding support structure 332, the position of the donor substrate 300 may be measured, such as by metrology tool 340C, to enable, for example, relative positioning between the donor substrate 300 and the acceptor substrate 350. The metrology tool 340C may be any appropriate metrology tool. The metrology tool 340C may measure locations of the donor die (e.g., the donor die 302A-302C), locations of the alignment point 315, etc. The metrology tool 340C may measure significantly fewer locations than the metrology tool 340A or 340B, and the controller may determine the position of the acceptor substrate 350 based on those fewer locations (e.g., from curve fitting, using physical deformation models, etc.). The controller may determine updated positions for the donor die (e.g., the donor die 302A-302C) based on a combination of the measured locations of the donor die 302A-302C (such as from Figure 3B) and the measured position of the donor substrate 300. The donor substrate 300 may experience deformation due to holding by a substrate chuck, the movement of the flipper 330, suspension from the bonding support structure 332, etc. The metrology tool 340C may also enable determination of deformation of the donor substrate by measuring locations. As noted above, the metrology tool 340C may measure significantly fewer locations than the metrology tools 340A and 340B, and the controller may determine the deformation of the donor substrate 300 based on those fewer locations (e.g., from curve fitting, using a physical deformation model, etc.) than those measured by the metrology tool 340A on the donor substrate 300 or by metrology tool 340B on the acceptor substrate 350.

[0080] In Figure 3G, the acceptor substrate 350 is supported by the substrate chuck 320B, which is supported by the support structure 322B. Once the position of the acceptor dies are measured, the substrate chuck 320B may be moved, such as to align with the donor substrate 300 supported by the flipper (e.g., supported by the bonding support structure 332 of Figure 3F). The support structure 322B may move (e.g., along direction 326) to the position of the support structure 322A, while the support structure 322A may move (e.g., along direction 325) to the position of the support structure 322B. The positions are provided as examples, and the support structures may move to different positions. For example, in some embodiments, the support structure 322A may move to a loading position, such as to receive an additional acceptor substrate (e.g., the acceptor substrate 350). The substrate chuck 320B may then occupy another position in the system 301 (e.g., a bonding position). The position the substrate chuck 320B moves to after measurement of the positions of the acceptor die (e.g., after the measurement depicted in Figure 3F) may be configured to place a donor die of the donor substrate 300 onto the acceptor die of the acceptor substrate 350. The substrate chuck 320B may be aligned with the donor substrate 300 in the flipper 330, which may be held above the plane of the substrate chuck 320B (as depicted in Figure 3G for a top down view in which the donor substrate 300 is at least partially above the plane of the substrate chuck 320B (e.g., obscuring the substratechuck 320A).

[0081] In Figure 3H, the donor substrate 300 and the acceptor substrate 350 are aligned. The donor substrate 300 may be aligned to the acceptor substrate 350 by movement of the bonding support structure 332, such as in any of the directions or orientations 333. The acceptor substrate 350 may be aligned with the donor substrate 300 by movement of a substrate chuck (e.g., the substrate chuck 320B of Figure 3G) or the support structure (e.g., the support structure 322B of Figure 3G). The donor substrate 300 and the acceptor substrate 350 may be aligned to one another, including by both coarse and fine alignment, such as by alignment of the relative positions of one or more alignment point (e.g., the alignment point 315 of the donor substrate 300 and the alignment point 317 of the acceptor substrate 350). In some embodiments, the donor substrate 300 and the acceptor substrate 350 may be aligned, such as by coarse alignment. In some embodiments, once the donor substrate 300 and the acceptor substrate 350 are aligned, one or more donor die of the donor substrate 300 may be aligned with one or more acceptor die of the acceptor substrate 350. In Figure 3H, the alignment of the donor die 302B with the acceptor die 304B (e.g., of the alignment point 303B of donor die 302B with the alignment point 305B of acceptor die 304B) is depicted. Once a donor die is aligned with a acceptor die, that donor die may be placed on the acceptor die, by any appropriate method, such as die actuator activation, gravitational acceleration, electrostatic actuation, etc. As described below, the system 301 also includes a self-alignment structure (not shown in Figure 3H) configured to cause self-alignment to control a relative position between the die and substrate during bonding (e.g., see at least Figures 4- 8).

[0082] In Figure 31, an additional donor substrate (e.g., donor substrate 300-2 having a carrier 314-2) is placed on the substrate chuck 320A for additional placement of donor dies on acceptor dies. In some embodiments, the additional donor substrate may be placed on the substrate chuck 320A after the substrate of the previous donor substrate is removed from the substrate chuck 320A — for example, if the substrate of a donor substrate is removed from the flipper 330 and re-placed on the substrate chuck 320A. In some embodiments, the previous donor substrate may be removed from the flipper 330 without recourse to the substrate chuck 320A, such as by removal from the flipper to an additional substrate chuck (not depicted) or any other appropriate removal procedure. The additional donor substrate may be placed on the substrate chuck 320A after the previous donor substrate is accepted by the flipper 330 or at any time when the substrate chuck 320A (or another substrate chuck) is free. The additional donor substrate (e.g., the donor substrate 300-2) may be substantially identical to or different from the previous donor substrate (e.g., the donor substrate 300). The processing of the donor substrate 300-2 by placement of the donor dies on acceptor dies may proceed as previously described in relation to Figures 3A-3H, such as by placement on an additional acceptor substrate (not depicted). The donor substrate 300-2 may be placed on the substrate chuck 320A while the donor dies of the donor substrate 300 are placed on the acceptor dies of the acceptor substrate 350, such as substantially simultaneously.

[0083] In Figure 3J, the positions of the donor die (e.g., the donor die 302A-2 to 302C-2) or of mark 315-2 are measured, as previously described in relation to Figure 3B.

[0084] In Figure 3J, additional donor die of the donor substrate 300 are placed on the acceptor die of the acceptor substrate 350. The position of the donor substrate 300, the acceptor substrate 350, or a combination thereof may be adjusted to align an additional donor die of the donor substrate 300 with a acceptor die of the acceptor substrate 350. As depicted, the donor substrate 300 is positioned (such as by movement in the directions or orientations 334) to align the alignment point 303A of the donor die 302A with the alignment point 305A of the acceptor die 304A. The donor die 302A may then be placed on the acceptor die 304A by any appropriate method, such as previously described. The donor die 302B is depicted as bonded to the acceptor die 304B, subsequent to their alignment at alignment point 307B in Figure 3H. As will be realized, the various steps of Figures 3A-H can be repeated as appropriate to bond multiple dies and process multiple donor and acceptor substrates.

[0085] Figures 4-12 illustrate additional details of the alignment system(s) and method(s) described above. Prior die-to-wafer bonding tools use guided alignment to position the dies. A donor die position and its bonding location on an acceptor wafer are measured, and used as input for a bonding transfer mechanism. The measurements and the transfer mechanism contribute to placement errors. Die-to-wafer bonding accuracy requirements are increasing, with placement accuracy down to 50 nm and below often required. Achieving this accuracy with existing die-to-wafer bonding tools is challenging. Figures 4-12 illustrate new systems and methods for die bonding self-alignment. As with guided alignment, a transfer mechanism moves the donor die in proximity to a desired acceptor location on an acceptor wafer, but then a self-alignment mechanism controls a relative position between substrates (e.g., a die and an acceptor wafer as one possibility) during the bonding. This enhances bonding placement accuracy compared to existing die-to-wafer bonding tools, among other advantages.

[0086] For example, Figure 4 illustrates another example embodiment of system 301 described above and shown in Figure 3A - 3J. In Figure 4, donor die 302A - 302C of the donor substrate 300 or carrier 314 are placed on the acceptor substrate 350. The position of the donor substrate 300, the acceptor substrate 350 (e.g., using bonding support structure 332 and / or a wafer stage 450 in this example), or a combination thereof may be adjusted to align donor die 302A-302C of the donor substrate 300. This may be accomplished using corresponding alignment points 303A-303C and 305A-305C, for example. As depicted, the donor substrate 300 is positioned (such as by movement in the directions or orientations 334 shown in Figure 3 J) to align the alignment point 303A of the donor die 302A with the alignment point 305A of the acceptor substrate 350. The donor die 302A may then be placed on the acceptor substrate 350 by any appropriate method, such as previously described. These steps can be repeated as appropriate to bond multiple dies and process multiple donor and acceptor substrates.

[0087] In this example, a structure 400A, 400B, or 400C is configured to cause self-alignment to control a relative position between semiconductor substrates (i.e., between donor die 302A and acceptor substrate 350, donor die 302B and acceptor substrate 350, or donor die 302C and acceptor substrate 350) during bonding. Structures 400A, 400B, or 400C may operate simultaneously, sequentially, or in other patterns, depending on the order of bonding operations (e.g., as described above). In some embodiments, the semiconductor substrates comprise a semiconductor die or a semiconductor wafer, such that bonding comprises die to wafer bonding, die to die bonding, or wafer to wafer bonding (die 302A, 302B, 302C to wafer or acceptor substrate 350 bonding is shown in Figure 4). In some embodiments, one of the semiconductor substrates comprises a semiconductor die (e.g., die 302A, 302B, or 302C), and another one of the semiconductor substrates (e.g., acceptor substrate 350) comprises an acceptor location. The one or more acceptor locations may be located on a semiconductor wafer, as shown in Fig. 1A-1D, 2A-2F, and 3A-3J, and described above, or in other locations. In Figure 4, acceptor locations are indicated by alignment points 305A, 305B, or 305C. The acceptor locations are on a semiconductor wafer (acceptor substrate 350) in this example. The one or more acceptor locations may also or instead comprise one or more corresponding acceptor semiconductor dies, for example. The structure 400A, 400B, or 400C causes self-alignment of the semiconductor die 302A - 302C relative to the acceptor location during transfer of the semiconductor die 302A - 302C to the acceptor location for bonding. The self-alignment is maintained in a period between release of the semiconductor die 302A - 302C and bonding of the semiconductor die to the acceptor location (on wafer or acceptor substrate 350. In some embodiments, the structure 400A, 400B, or 400C comprises a first self-alignment pattern 401A, 401B, or 401C on an acceptor location facing surface 403A, 403B, or 403C of a first semiconductor substrate (e.g., die 302A, 302B, or 302C), and a corresponding second self-alignment pattern 405 A, 405B, or 405C, on a first semiconductor substrate facing surface 407A, 407B, or 407C of a second semiconductor substrate (e.g., acceptor substrate 350), at the acceptor location (e.g., at or near alignment points 305A, 305B, or 305C), to interact with the first self-alignment pattern 401A, 401B, or 401C.

[0088] Figure 5 illustrates several examples of possible first self-alignment patterns 401A, 40 IB, or 401C and the corresponding second self-alignment patterns 405A, 405B, or 405C. Each pattern is shown in perspective view. Upper and lower patterns in each set of two patterns correspond to each other. The patterns may have many different forms, have different shapes, or have different sizes. In some embodiments, a first self-alignment pattern 401A, 401B, or 401C and the corresponding second self-alignment pattern 405 A, 405B, or 405C each repeats in two dimensions (e.g., see the alternating dark and light patters in horizontal and vertical directions), or comprises separate pattern portions for the two dimensions (e.g., see the vertical portions and separate horizontal portions in two of the examples) such that the exact negative of a pattern is not needed for self-alignment. In some embodiments, the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric (e.g., see oppositely alternating dark and light patterning in each pattern). In someembodiments, the first self-alignment pattern and the corresponding second self-alignment pattern are not mirror symmetric For example, alignment may be performed with partial features on one of the two sides (e.g., in the bottom most images in Figure 5, the “F” shape may be missing the middle stripe in the acceptor or donor, or in the upper right images, the inner circle may be omitted, etc.). Known lithography, etching, and / or other techniques may be used to create these features for self-alignment (to achieve nanometer resolution, nanometer ‘guiding’ structures are also needed).

[0089] In some embodiments, the structure 400A, 400B, or 400C is configured such that the first self-alignment pattern 401A, 401B, or 401C and the corresponding second self-alignment pattern 405A, 405B, or 405C are electrostatically activated. In some embodiments, the first self-alignment pattern 401A, 401B, or 401C is positively charged, and the corresponding second self-alignment pattern 405A, 405B, or 405C is negatively charged, or vice versa. In some embodiments, the first self-alignment pattern 401A, 401B, or 401C and the corresponding second self-alignment pattern 405A, 405B, or 405C comprise electrically conductive pads. A potential difference across the electrically conductive pads may form a capacitor and provide the self-alignment, for example.

[0090] For example, Figure 6 illustrates a structure 400A, 400B, or 400C comprising an electrostatically activated arrangement 600. Arrangement 600 comprises electrostatic clamps 602, a donor carrier 314 and donor die 302, an acceptor carrier 608 (e.g., similar to or the same as acceptor substrate 350 or stage 450 shown in Figure 4) and acceptor die 304, a voltage source 612, and other components. In this example, opposite charges 614 induced on the first self-alignment pattern 401 A, 401B, or 401C and the corresponding second self-alignment pattern 405A, 405B, or 405C attract the dies 302 and 304, and facilitate self-alignment. Opposite charges are induced on the first selfalignment pattern 401A, 401B, or 401C and the corresponding second self-alignment pattern 405A, 405B, or 405C, which attract the donor die 302 and the acceptor die 304 toward each other when they reach a position during the bonding process where the positively and negatively charged fields can interact. The magnetic interaction facilitates self-alignment. For example, as described above, a transfer mechanism may move the donor die 302 in proximity to the acceptor die 304 on acceptor carrier 608, and then the magnetic self-alignment controls a relative position between the two dies during the bonding. Electrostatic forces direct the donor die 302 to its final position in this example.

[0091] Figure 7 illustrates an example structure 400A, 400B, or 400C that facilitates hydrophilic- hydrophobic self-alignment 700. As shown in Figure 7, in some embodiments, the first selfalignment pattern 401A, 401B, or 401C comprises a hydrophilic material, and the corresponding second self-alignment pattern 405A, 405B, or 405C comprises a hydrophobic material, or vice versa. There may be a fluid (e.g., liquid or gas) layer 702 between a first semiconductor substrate (donor die 302A, 302B, or 302C in this example) and a second semiconductor substrate (a wafer or acceptor substrate 350 in this example) with the self-alignment patterns. Patterns 401A, 401B, or 401C and 405A, 405B, or 405C may be created on donor die 302A, 302B, or 302C and wafer or acceptor substrate 350 made of hydrophilic and hydrophobic materials. When the donor and acceptor arebrought in contact with fluid layer 702 (e.g., a thin layer of water) in between, the die 302A, 302B, or 302C is configured to float (self-align) to a final position. The fluid layer may be removed by evaporation or other removal techniques, for example.

[0092] Figure 8 illustrates an example structure 400A, 400B, or 400C with a first self-alignment pattern 401A, 401B, or 401C comprising a donor mechanical structure 800, and a corresponding second self-alignment pattern 405A, 405B, or 405C comprising an acceptor mechanical structure 802. In some embodiments, the donor mechanical structure 800 and the acceptor mechanical structure 802 comprise corresponding studs and recesses or other components. This is a two dimensional example shown in side view. However, multiple rows and / or columns of a plurality of studs and corresponding recesses may be used. The corresponding studs and / or recesses may have generally cylindrical, triangular, rectangular, trapezoidal, cone, domed, and / or other shapes. Figure 8 illustrates a generalized shape having a rectangular or cylindrical cross section in the primary image, but also provides additional examples of a cone / trapezoid 810, and a dome 820 structure.

[0093] Self-alignment may be most easily achieved with cone shapes, but other shapes are possible. In some embodiments, one shape may be used for the studs, and a different shape may be used for the recesses (e.g., as shown at 810 and 820 in Figure 8). Studs and corresponding recesses may be located on either one of a donor substrate or an acceptor substrate. For example, to facilitate selfalignment, studs may be located on an acceptor wafer, with corresponding orifices on a donor die. The studs may have a cylindrical pillar shape, with the orifices having a corresponding shape, but with chamfered or widened edges around the orifice to help guide the studs into place. Tolerances of the mechanical structures 800 and 802 may be configured such that donor and acceptor substrates (e.g., dies, wafers, etc.) stick together when mechanical structures are coupled. The number of studs and corresponding recesses on a donor die or an acceptor wafer (as one example) may depend on an amount of available space on the die or wafer, or on other factors.

[0094] As additional examples, the shapes, sizes, materials, or other characteristics of the studs or recesses may be configured based on an amount of force with which a donor die (or other substrate) and an acceptor die (or other substrate) are coupled. The force may be provided by a handling mechanism (e.g., as described above), a radiation mediated release mechanism (as described below), or other mechanisms. In some embodiments, a tensile strength of the material of the studs is configured to prevent breakage during self-alignment, for example. The tensile strength of silicon dioxide (as one possibility) is above 300 MPa. The dimensions of the studs are also important. For 50 nm bonding accuracy, cylindrical studs with a diameter of about 20 nm configured to engage corresponding recesses with an initial diameter of 50 nm, which taper down to 20 nm, may be used for example. Similar configurations with trapezoidal, cone shaped, or other studs and recesses may be used. Other arrangements are also contemplated.

[0095] The studs and / or recesses may be configured (e.g., using a certain material or materials, different dimensions, and / or other configurable characteristics) such that they do not have too high afriction coefficient to prevent a donor die and acceptor die (e.g., having the studs and recesses, respectively, in this example) from getting ‘stuck’, instead of sliding into place. More force may also and / or instead be applied overcome any such “stickiness”, but care should be taken not to break the donor and / or acceptor die.

[0096] Spacing is important and related to the accuracy of the tool. The spacing of the studs and / or recesses may be configured to avoid self-aligning a stud in row X to a recess in row X+l or X+2, for example. For example, studs and corresponding recesses may be arranged in a pattern for a selfaligning structure such that it is not possible to misalign studs and corresponding recesses (e.g., in a patter similar to a QR code structure, which is unique, as one possibility of many, such that either all studs fit inside the corresponding recesses or none / or only a small amount fit).

[0097] Returning to Figure 4, in some embodiments, the self-alignment structure comprises a first self-alignment pattern 475 on an acceptor location facing surface 477 of a holder (substrate 300) or carrier 314 of a first semiconductor substrate (e.g., a donor die 302A, 302B, or 302C), and a corresponding second self-alignment pattern 479, on a first semiconductor substrate facing surface 481 of a holder or carrier (stage 450) of a second semiconductor substrate (wafer or acceptor substrate 350), to interact with the first self-alignment pattern 475. The first self-alignment pattern 475 and the corresponding second self-alignment pattern 479 may be mirror symmetric. The first self-alignment pattern 475 and the corresponding second self-alignment pattern 479 may be electrostatically activated. For example, the first self-alignment pattern 475 may be positively charged, and the corresponding second self-alignment pattern 479 may be negatively charged, or vice versa. In some embodiments, the first self-alignment pattern 475 and the corresponding second self-alignment pattern 479 may comprise electrically conductive pads. The first self-alignment pattern 475 may comprise a hydrophilic material, and the corresponding second self-alignment pattern 479 may comprise a hydrophobic material, or vice versa. In some embodiments, the first self-alignment pattern 475 comprises a donor mechanical structure, and the corresponding second self-alignment pattern 479 comprises an acceptor mechanical structure, or vice versa.

[0098] Figures 9A-9D are schematic diagrams illustrating an example method for die bonding (similar to what is shown in Figure 4) with radiation mediated release in combination with selfalignment structures 400 (e.g., 400A, 400B, or 400C illustrated and discussed above). Figures 9A-9D are cross-sectional views of bonding of a donor die 302 to an acceptor die 304 (e.g., an acceptor location) by radiation-mediated release. Figures 9A-9D are described with reference to “donor die” and “acceptor die”, which are relative descriptors as used herein and the donor die may instead be an acceptor die and vice versa. A donor die may instead be a donor substrate and an acceptor die may instead be an acceptor substrate (e.g., another example acceptor location) and a donor die may be bonded to an acceptor substrate, a donor substrate may be bonded to an acceptor substrate, and a donor substrate may be bonded to an acceptor die. Multiple donor dies may be bonded to a singleacceptor die and vice versa. Radiation-mediated release may be used with any appropriate die bonding method, such as any of those previously described.

[0099] In Figure 9A, the donor die 302 is supported by a carrier 314. In Figure 9A-9D the carrier 314 is transparent to at least a range of radiation (e.g., electromagnetic radiation, visible light, UV radiation, a particle or electron beam, etc.). The carrier 314 may be transparent to visible light, infrared radiation, ultraviolet radiation, a particle or electron beam, etc. The carrier 314 may be fabricated of any appropriate material, such as glass, silicon dioxide, sapphire, acrylic, etc. The carrier 314 may be a flexible substrate, such as a flexible polymer supported by a superstructure (such as a substrate chuck with one or more radiation windows). The carrier 314 may be a substantially inflexible substrate. The thickness of the carrier 314 (e.g., in the Z direction) may vary depending on which type of material the carrier 314 is fabricated from, such as where thickness may be selected based on deformation thresholds, electromagnetic radiation extinction coefficients, etc.

[0100] In an embodiment, the donor die 302 is adhered to the carrier 314 by, e.g., a layer of adhesive 950. Herein, “adhered” encompasses holding of one material to another in a manner which is releasable, including where the release is chemically, physically, electrically, etc. mediated. The adhesive 950 may be any appropriate adhesive, such as an organic glue, a polymer glue, etc. The adhesive 950 may be applied to the carrier 314 (such as by spin coating) and then the donor die 302 applied to the adhesive 950 on the substrate. The adhesive 950 may be applied to a surface of the donor die 302 (such as by ink jetting, dipping, etc.) and then the donor die 302 and adhesive 950 transferred to the carrier 314.

[0101] The adhesive 950 may be of any appropriate thickness. The adhesive 950 may be an adhesive which forms a gas when exposed to radiation or heat. For example, the adhesive 950 may be an adhesive which experiences a phase change (such as at atmospheric temperature and pressure) from solid or liquid to gas when excited by a burst of radiation or heated by such a burst of radiation. The adhesive 950 may be an adhesive which experiences a chemical change (such as a decomposition) which forms gas when excited by a burst of radiation or heated by such a burst. In some embodiments, the adhesive 950 may expand in volume without forming a gas or only partially forming a gas when exposed to radiation or heat. For example, the adhesive 950 may contain a dissolved gas which may partially precipitate when exposed to radiation or heat and which may create bubbles within the adhesive 950 thereby increasing the volume occupied by the adhesive. The adhesive 950 may be any appropriate material which experiences radiation -mediated volume expansion. The carrier 314 may be transparent to radiation of a wavelength which causes radiation- mediated volume expansion in the adhesive 950.

[0102] In Figure 9A and 9B, the donor die 302 is aligned with the acceptor die 304. The alignment may be performed by any appropriate method, such as any of those previously described. An alignment point 903 of the donor die 302 may be aligned with an alignment point 905 of the acceptor die 304 to become aligned as shown by alignment 907. The alignment may be accomplished bymovement of the carrier 314 supporting the donor die 302 and / or by a carrier structure (stage 450) supporting the acceptor die 304. The donor die 302 may be prepared for bonding with the acceptor die 304 (and vice versa) such as by atomic level cleaning and flatness treatment. The donor die 302 and the acceptor die 304 may bond with each other by, e.g., Van der Waals bonding when brought into proximity (e.g., to within the order of a van der Waals contact distance, such as within twice the van der Waals contact distance but larger than once the van der Waals contact distance) and with sufficient other conditions, such as matching shape (which need to be flat), smoothness, etc. The donor die 302 and the acceptor die 304 may be subsequently annealed (e.g., heated) to create or enhance an electrical bond between regions of the donor die 302 and the acceptor die 304 (such as described in reference to Figures 1A-1C).

[0103] In Figure 9B, radiation 920 is applied to the adhesive 950. The radiation 920 may be a burst of radiation (e.g., a shot of radiation), which may be applied to the adhesive 950 to initiate the radiation -mediated bonding process or throughout the radiation -mediated bonding process. The radiation 920 may be part of a larger radiation pattern, which may be non-uniform over the donor die 302, over the carrier 314, etc. The radiation 920 may be directed at a central portion of the donor die 302, at an edge or comer of the donor die 302, etc. The radiation 920 may be a scanning beam, i.e., there is relative movement between the radiation 920 and the donor die 302. The radiation 920 may be variable, such as a subject to Gaussian intensity variation. The radiation 920 may be applied in a direction 922 substantially perpendicular (e.g., within 10 degrees thereof) to the carrier 314 (e.g., substantially perpendicular to a planar face of the donor die 302 in contact with the adhesive 950). In an embodiment, there is relative movement between the radiation 920 and the donor die 302 so as to cause different portions of the face of the donor die 302 to come in subsequent contact with the acceptor die 304 - in effect, “rolling on” the donor die to the acceptor die. The “rolling on” can be from one edge of the donor die toward another edge of the donor die or can be outwards from a central portion of the donor die to one or more edges of the donor die as depicted in Figures 9C and 9D.

[0104] The application of the radiation 920 to the adhesive 950 may generate a gas (or other volumetric expansion as previously described) “bubble”, such as bubble 952. The bubble 952 may occupy the entire thickness of the adhesive 950 (e.g., the entire adhesive layer may be decomposed into gas) or a partial thickness of the adhesive 950 (e.g., as depicted). The bubble 952 may cause deformation of the backside 954 of the donor die 302 (e.g., the face of the donor die 302 in contact with the adhesive 950). The bubble 952 may also cause deformation of the frontside 956 of the donor die 302, which may approach the acceptor die 304 because of the deformation. The deformation of the donor die 302 may depend on the thickness of the adhesive 950 and the amount of adhesive 950 decomposed to gas or volumetrically expanded as well as the thickness and size of the donor die 302. For example, a 3 by 3 mm die of 1.5 pm thickness may experience up to 4 pm of bending (e.g., in the Z direction) due to 1 Pa of pressure created in the bubble 952.

[0105] In this example, the structure 400 is configured to cause self-alignment to control a relative position between semiconductor substrates (i.e., between donor die 302 and acceptor die 304) during bonding. In some embodiments, the radiation 920 is provided to cause transfer of two or more donor dies at a substantially same time, and self-alignment is maintained during transfer for each of the two or more dies.

[0106] As depicted in Figure 9C, there may be relative movement between the radiation 920 and the surface of the donor die 302 and adhesive 950 (e.g., movement of donor die 302 and / or a delivery spot of radiation 920 in the direction 924), such as to cause more decomposition or volumetric expansion of the adhesive 950 and increase the size of the bubble 952. As the bubble 952 increases, the donor die 302 may bend such that self-alignment structure 400 begins to function just before the donor die 302 contacts the acceptor die 304, at contact point 958. Once the donor die 302 contacts the acceptor die 304, a bonding wavefront may emanate from the contact point 958 causing generation of van der Waals bonds between atoms of the surface of the donor die 302 and the acceptor die 304. The bonding wavefront may be encouraged, channeled, shaped, etc. by one or more various surface treatments on the donor die 302 and acceptor die 304. The donor die 302 may be in contact with both the carrier 314 and the acceptor die 304, and may therefore not be substantially free-floating during the bonding process.

[0107] As depicted in Figure 9D, once the bubble 952 is of sufficient size or the contact between the donor die 302 and the acceptor die 304 is of large enough area, the donor die 302 may release from the carrier 314. The release of the donor die 302 from the substrate may allow the gas to escape from the bubble 952. The donor die 302 may fall flat onto the acceptor die 304 (e.g., an acceptor location 962), for example the spring constant of the donor die 302 causes release of the deformation of the donor die 302 due to the bubble 952.

[0108] Figures 10A-10D are schematic diagrams illustrating an example method for die bonding with radiation mediated release, a flexible interposer layer, and self-alignment structures 400 (e.g., 400A, 400B, or 400C illustrated and discussed above). Figures 10A-10D are cross-sectional views of bonding of a donor die (e.g., donor die 302) to an acceptor die 304 (or acceptor location) by radiation- mediated release in the case of, for example, a substantially inflexible donor die 302. Figures 10A- 10D are described with reference to “donor die” and “acceptor die”, which are relative descriptors as used herein and donor die may instead be acceptor die and vice versa. A donor die may instead be a donor substrate and an acceptor die may instead be an acceptor substrate (also an acceptor location) and a donor die may be bonded to an acceptor substrate, a donor substrate may be bonded to an acceptor substrate, or a donor substrate may be bonded to an acceptor die. Multiple donor dies may be bonded to a single acceptor die and vice versa. Radiation-mediated release may be used with any appropriate die bonding method, such as any of those previously described.

[0109] In Figure 10A, the donor die 302 is supported by a carrier 314. The carrier 314 may be any appropriate substrate for radiation-mediated release, such as previously described. The donor die 302may be inflexible, such as due to donor die thickness, donor die material, etc. The donor die 302 may be placed on a flexible interposer 1070. The flexible interposer 1070 may act as a flexible layer. The donor die 302 may be adhered to the flexible interposer 1070 by any appropriate means, such as by adhesive, electrostatic attraction, etc. The donor die 302 may be adhered to the flexible interposer 1070 in one or more locations but otherwise free floating. The donor die 302 may be lightly (e.g., separable) adhered to the flexible interposer 1070, such that the donor die 302 may peel off (e.g., separate) from the flexible interposer 1070 due to flexion of the flexible interposer 1070. The flexible interposer 1070 may be optically opaque, including reflective, such that radiation transmitted through the carrier 314 does not reach any adhesive between the flexible interposer 1070 and the donor die 302. In some embodiments, the flexible interposer 1070 may be adhered to the donor die 302 and the carrier 314 by the same method (e.g., by adhesive 950).

[0110] The flexible interposer 1070 is adhered to the carrier 314 by a layer of any appropriate adhesive 950. The donor die 302 is aligned with the acceptor die 304, which can be supported by a carrier (e.g., stage 450). The alignment may be performed by any appropriate method, such as any of those previously described. An alignment point 903 of the donor die 302 may be aligned with an alignment point 905 of the acceptor die 304 to realize alignment 907 as shown in Figure 10B. The donor die 302 may be prepared for bonding with the acceptor die 304 (and vice versa) such as by atomic level cleaning and flatness treatments. The donor die 302 and the acceptor die 304 may bond with each other by Van der Waals bonding when brought into proximity (e.g., contact). The donor die 302 and the acceptor die 304 may be subsequently annealed (e.g., heated) to create or enhance an electrical bond between regions of the donor die 302 and the acceptor die 304 (such as described in reference to Figure 1A-1C). The donor die 302 may be a substantially inflexible die. For example, the donor die 302 may have a thickness of 4 pm or thicker, 10 pm or thicker, 100 pm of thicker, 500 pm or thicker, 1000 pm or thicker, etc., where the thickness at which a die is considered inflexible may vary based on die material, die size (e.g., surface area), flexion force, etc.

[0111] In Figure 10B, radiation 920 is applied to the adhesive 950. The radiation 920 may be any appropriate radiation, such as described in reference to radiation 920 of Figure 9B. The radiation 920 may be a burst of radiation (e.g., a shot of radiation), which may be applied to the adhesive 950 to initiate the radiation -mediated bonding process or throughout the radiation -mediated bonding process. The radiation 920 may be part of a larger radiation pattern, which may be non-uniform over the donor die 302, over the carrier 314, etc. The radiation 920 may be directed at a central portion of the donor die, at an edge or comer of the donor die, etc. The radiation 920 may be a scanning beam, i.e., there is relative movement between the radiation 920 and the donor die 302. The radiation 920 may be variable, such as a subject to Gaussian intensity variation. The radiation 920 may be applied in a direction 922 substantially perpendicular (e.g., within 10 degrees thereof) to the carrier 314 (e.g., substantially perpendicular to a planar face of the donor die 302 in contact with the flexible interposer 1070). In an embodiment, there may be relative movement between the radiation 920 and the donordie 302 so as to cause different portions of the face of the donor die 302 to come in subsequent contact with the acceptor die 304 - in effect, “rolling on” the donor die to the acceptor die. The “rolling on” may be from one edge of the donor die toward another edge of the donor die, e.g., the flexible interposer 1070 may flex to allow an edge of the donor die to contact the acceptor die and then further flexes as there is relative displacement between the radiation and the donor die so to cause a further portion of donor die to contact the acceptor die.

[0112] The application of the radiation 920 to the adhesive 950 may generate a gas (or other volumetric expansion as previously described) “bubble”, such as bubble 952. The bubble 952 may occupy the entire thickness of the adhesive 950 (e.g., the entire adhesive layer may be decomposed into gas) or a partial thickness of the adhesive 950 (e.g., as depicted). The bubble 952 may cause deformation of the backside 1054 of the flexible interposer 1070 (e.g., the face of the flexible interposer 1070 in contact with the adhesive 950). The bubble 952 may also cause deformation of the frontside 1056 of the flexible interposer 1070 (e.g., the face of the flexible interposer 1070 in contact with the donor die 302). The deformation of the flexible interposer 1070 may cause movement of the donor die 302, such as towards the acceptor die 304. The deformation of the flexible interposer 1070 may cause separation of portions of the flexible interposer 1070 from the donor die 302. The deformation of the flexible interposer 1070 may cause the alignment point (e.g., alignment point 903 of Figure 10A) of the donor die 302 to approach the alignment point (e.g., alignment point 905 of Figure 10A) of the acceptor die, resulting in alignment 907. The amount of deformation of the flexible interposer 1070 may depend on the thickness of the adhesive 950 and the amount of adhesive 950 decomposed to gas or volumetrically expanded as well as the thickness and size of the flexible interposer. For example, a 3 by 3 mm flexible interposer of 1.5 pm thickness may experience up to 4 pm of bending (e.g., in the Z direction) due to 1 Pa of pressure created in the bubble 952. The flexible interposer 1070 is depicted as having the same area as the donor die 302, but may instead be smaller or larger than the donor die 302.

[0113] In this example, the structure 400 is configured to cause self-alignment to control a relative position between semiconductor substrates (i.e., between donor die 302 and acceptor die 304) during bonding. In some embodiments, the radiation 920 is provided to cause transfer of two or more donor dies at a substantially same time, and self-alignment is maintained during transfer for each of the two or more dies.

[0114] As depicted in Figure 10C, there may be relative movement between the radiation 920 and the surface of the flexible interposer 1070 and adhesive 950 (e.g., movement of the donor die 302 and / or delivery spot of the radiation 920 in the direction 924), such as to cause more decomposition or expansion of the adhesive 950 and increase the size of the bubble 952. As the bubble 952 increases, the flexible interposer 1070 may bend such that self-alignment structure 400 begins to function just before the donor die 302 contacts the acceptor die 304, such as during alignment 907. Once the donor die 302 contacts the acceptor die 304, a bonding wavefront may emanate from the contact point (e.g.,see alignment 907) causing generation of van der Waals bonds between atoms of the surface of the donor die 302 and the acceptor die 304. The bonding wavefront may be encouraged, channeled, shaped, etc. by one or more various surface treatments on the donor die 302 and acceptor die 304. In some embodiments, due to the inflexibility of the donor die 302, the donor die 302 may contact multiple, substantially most or all contact points of the acceptor die 304 simultaneously, in which case multiple bonding wavefronts may emanate from the multiple contact point or which may even prevent bonding wavefronts due to simultaneity of bonding. The donor die 302 may be in contact with both the flexible interposer 1070 and the acceptor die 304, with the flexible interposer in contact with both the donor die 302 and the carrier 314, and therefore the donor die 302 may not be substantially free- floating during the bonding process.

[0115] As depicted in Figure 10D, once the bubble 952 is of sufficient size or the contact between the donor die 302 and the acceptor die 304 is of large enough area, the flexible interposer 1070 may release from the carrier 314. The release of the flexible interposer 1070 from the substrate may allow the gas to escape from the bubble 952. The donor die 302 and flexible interposer 1070 may fall flat onto the acceptor die 304, for example the spring constant of the flexible interposer 1070 may cause release of the donor die 302 due to the bubble 952. The flexible interposer 1070 may be removed from the donor die 302, such as by dissolution of remaining adhesive or other adhesion method. The flexible interposer 1070 may alternatively or additionally remain on the donor die 302, such as a passivation layer. In an embodiment, the flexible interposer 1070 may remain attached to the carrier 314 and the donor die 302 releases from the flexible interposer 1070.

[0116] Figure 11 is a flowchart which illustrates an exemplary method of self-alignment and placement of one or more semiconductor donor dies. Each of these operations is described in detail below. The operations of method 1100 presented below are intended to be illustrative. In some embodiments, method 1100 may be accomplished with one or more additional operations not described, or without one or more of the operations discussed. Additionally, the order in which the operations of method 1100 are illustrated in Figure 11 and described below is not intended to be limiting. In some embodiments, one or more portions of method 1100 may be implemented by one or more systems described herein, such as system 301 shown in Figure 3A - 3J and Figure 4-10, and described above, for example. In some embodiments, one or more portions of method 1100 may be implemented (e.g., by simulation, modeling, etc.) in one or more processing devices (e.g., one or more processors or a processor system that forms, or forms part of computer system CS shown in Figure 12 and described below). The one or more processing devices may include one or more devices executing some or all of the operations of method 1100 in response to instructions stored electronically on an electronic storage medium. The one or more processing devices may include one or more devices configured through hardware, firmware, or software to be specifically designed for execution of one or more of the operations of method 1100, for example.

[0117] At an operation 1110, a plurality of donor die locations are obtained. The donor die locationsmay be obtained via measurement of one or more positions of the donor dies along one or more dimensions. The donor dies may lie on or be part of a donor substrate (e.g., a carrier, a semiconductor substrate, etc.), and the locations of the plurality of donor dies may be obtained with respect to that donor substrate. The locations of the plurality of donor die may be measured with respect to a measurement mark. The locations of the plurality of donor dies may be measured in-plane (e.g., in the x-y plane). The locations of the plurality of donor dies may also be measured via a first method inplane and measured out of plane (e.g., in the Z direction) via a second method. For example, the locations of the plurality of donor dies may be measured based on one or more images in -plane. The locations of the plurality of donor dies may be obtained from a two-dimensional image, which may show locations of an edges or comer of a donor die with respect to positions on a support structure or on a die actuator. The locations of the plurality of donor dies may be obtained based on one or more features (for example, one or more electrically active areas) on an exposed surface of the donor die. These one or more features of the donor die may be used as an alignment mark or reference mark. In some embodiments, alignment marks may be included as exposed features of the donor die. The alignment marks may be specifically added for die bonding or may be alignment marks corresponding to previous fabrication steps. The plurality of donor die locations may be measured or obtained from storage.

[0118] At an operation 1120, one or more corresponding acceptor die locations (e.g., acceptor locations) are obtained. The acceptor dies may lie on or be part of an acceptor substrate (e.g., a carrier, a semiconductor substrate, etc.), and the locations of the plurality of acceptor dies may be obtained with respect to that acceptor substrate. The locations of the plurality of acceptor die may be obtained in any appropriate method, including any of those described in reference to the operation 1010.

[0119] At an operation 1130, one or more donor dies are selected from the plurality of donor dies. The one or more donor dies may be selected based on position (e.g., along a row, along a column), displacement (e.g., donor die closest to an ideal position), thickness (e.g., thicker dies may be placed before thinner dies, including if donor dies include two or more types of dies), etc. A donor die may have a corresponding acceptor die, such as an acceptor die in a corresponding location on an acceptor substrate (e.g., acceptor die carrier structure). In some embodiments, an acceptor die may be selected, by any appropriate method, and a donor die selected based on its correspondence to the selected acceptor die. The one or more donor dies and the acceptor die(s) may be brought together such that a donor die and its corresponding acceptor die are separated by a distance which may be traversed by the die placement method. The donor die and acceptor die may be grossly aligned (e.g., coarse aligned), such as to within a threshold of coarse alignment. The donor die and acceptor die may be held in proximity by one or more substrates, chucks, actuators, adhesives, etc.

[0120] At an operation 1140, the relative position between a selected donor die and a corresponding acceptor die is adjusted to have alignment between the donor die and the corresponding acceptor die. Adjusted includes cases in which locations are minimally or substantially not adjusted (e.g., aftermeasurement or bringing into proximity), such as if a measured location corresponds to the acceptor location within a threshold. In an embodiment, the position of the donor die may be adjusted by action of a die actuator, a substrate holder, a chuck, etc. The position of the donor die may be adjusted by action of a substrate handling apparatus. The position of the donor die may be adjusted in one or more directions, such as in the X-Y plane. Alternatively or additionally to adjustment of the location of the donor die, the position of the acceptor die may be adjusted, by any appropriate method, such as any of those previously described. Adjustment of the relative position between the donor and acceptor die may include iterative measurement of donor or acceptor die location, including as adjustment occurs.

[0121] Adjustment of the location of the donor die may occur based on an alignment location for the donor die. The alignment location may be an acceptor (e.g., acceptor location) for placement of the donor die. An acceptor (e.g., acceptor location) may be obtained, such as at operation 1120, from measurement of the acceptor die position. The acceptor may correspond to a location of the acceptor die. The acceptor may correspond to a plurality of locations on the acceptor die. The acceptor may be a position (e.g., a position in three dimensions such as along X, Y, and Z axes, positions in six directions such as along X, Y, and Z axes and with respect to angles of rotation about those axes, etc.). The acceptor may be a set of positions, for example two or more positions of or on an acceptor die to which areas of the donor die are to be bonded. Additionally or alternatively, adjustment of the location of the acceptor die may occur based on an alignment location for the acceptor die. The alignment location may be an acceptor (e.g., acceptor location) for placement of the donor die. An acceptor (e.g., acceptor location) may be obtained, such as at operation 1110, from measurement of the donor die position. The acceptor may correspond to a location of the donor die. The acceptor may correspond to a plurality of locations on the donor die.

[0122] At an operation 1150, a selected donor die (or one or more donor dies) is placed on a corresponding acceptor die (or one or more acceptor dies). The donor die may be placed on the acceptor die by any appropriate method, such as by movement of a die actuator, by radiation-mediated bonding, by stamping, by electrostatic attraction, etc. The donor die may experience alignment, including self-alignment (e.g., as described herein), as the donor die is brought into contact with the acceptor die. The donor die may be adhered to the acceptor die as it contacts the acceptor die, such as by van der Waals forces. In some embodiments, an additional donor die may be placed on the same or different acceptor die.

[0123] At an operation 1160, it is determined if additional donor die remain for placement. If additional donor die (e.g., on the donor substrate or carrier) remain for placement, the flow continues to the operation 1130 where another donor die is selected. If no additional donor die remain for placement, flow continues to operation 1170, where the bonding of the plurality of dies is completed.

[0124] In an embodiment, a particular donor die and acceptor die are bonded at the time the donor die is placed on the acceptor die, e.g., through intermolecular bonding. In an embodiment, the donor die is bonded, such as through annealing or other bonding process, to the acceptor die after placementof the donor die on the acceptor die. In an embodiment, a bonding of a donor and acceptor die is completed before a next donor die is placed on an acceptor die. In an embodiment, bonding of a donor and acceptor die is completed after a plurality of donor dies are placed on respective acceptor dies, e.g., after all the donor dies on a donor substrate or carrier are placed. In an embodiment, a donor die placed on a acceptor die is annealed to form or enhance electrical connection. In an embodiment, the annealing of a particular donor die and acceptor die can be done prior to a next donor die is placed on a acceptor die. In an embodiment, annealing of a donor and acceptor die is completed after a plurality of donor dies are placed on respective acceptor dies, e.g., after all the donor dies on a donor substrate or carrier are placed. The donor die may be held against the acceptor die for a bonding or annealing time period. A donor die and acceptor die pair may be released from a substrate or other holding apparatus before annealing or after annealing has occurred.

[0125] Figure 12 is a diagram of an example computer system CS that may be used to implement one or more of the operations described herein. The computer system CS may be, include, or be included in the controller of the system 301 shown in Figure 3 A - 3 J and described above, or other systems described herein. For example, computer system CS may form a processor system that controls or performs other functions associated with one or more components of the system 301. Computer system CS includes a bus BS or other communication mechanism for communicating information, and a processor PRO (or multiple processors) coupled with bus BS for processing information. Computer system CS also includes a main memory MM, such as a random-access memory (RAM) or other dynamic storage device, coupled to bus BS for storing information and instructions to be executed by processor PRO. Main memory MM also may be used for storing temporary variables or other intermediate information during execution of instructions by processor PRO. Computer system CS further includes a read only memory (ROM) ROM or other static storage device coupled to bus BS for storing static information and instructions for processor PRO. A storage device SD, such as a magnetic disk or optical disk, is provided and coupled to bus BS for storing information and instructions.

[0126] Computer system CS may be coupled via bus BS to a display DS, such as a cathode ray tube (CRT) or flat panel or touch panel display for displaying information to a computer user. An input device ID, including alphanumeric and other keys, is coupled to bus BS for communicating information and command selections to processor PRO. Another type of user input device is cursor control CC, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor PRO and for controlling cursor movement on display DS. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane. A touch panel (screen) display may also be used as an input device.

[0127] In some embodiments, portions of one or more methods described herein may be performed by computer system CS in response to processor PRO executing one or more sequences of one ormore instructions contained in main memory MM. Such instructions may be read into main memory MM from another computer-readable medium, such as storage device SD. Execution of the sequences of instructions included in main memory MM causes processor PRO to perform one or more process steps (operations) described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory MM. In some embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, the description herein is not limited to any specific combination of hardware circuitry and software.

[0128] Further embodiments are disclosed in the list of numbered clauses below:1. A method for bonding semiconductor substrates, the method comprising: causing self-alignment to control a relative position between the semiconductor substrates during the bonding.2. The method of clause 1, wherein the semiconductor substrates comprise a semiconductor die or a semiconductor wafer, such that bonding comprises die to wafer bonding, die to die bonding, or wafer to wafer bonding.3. The method of any of the preceding clauses, wherein: one of the semiconductor substrates comprises a semiconductor die, and another one of the semiconductor substrates comprises an acceptor location; and the method comprises causing self-alignment of the semiconductor die relative to the acceptor location during transfer of the semiconductor die to the acceptor location for bonding.4. The method of clause 3, wherein the self-alignment is maintained in a period between release of the semiconductor die and bonding of the semiconductor die to the acceptor location.5. The method of clause 3 or clause 4, wherein the acceptor location is on a semiconductor wafer.6. The method of any of clauses 3-5, wherein the acceptor location comprises a second semiconductor die.7. The method of any of the preceding clauses, wherein the self-alignment is caused by: a first self-alignment pattern on an acceptor location facing surface of a first semiconductor substrate, and a corresponding second self-alignment pattern, on a first semiconductor substrate facing surface of a second semiconductor substrate, at the acceptor location, to interact with the first selfalignment pattern.8. The method of clause 7, wherein the first self-alignment pattern and the corresponding second self-alignment pattern each repeats in two dimensions, or comprises separate pattern portions for the two dimensions such that an exact negative of a pattern is not needed for self-alignment.9. The method of clause 7 or clause 8, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric.10. The method of any of clauses 7-9, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are electrostatically activated.11. The method of clause 10, wherein the first self-alignment pattern is positively charged, and the corresponding second self-alignment pattern is negatively charged, or vice versa.12. The method of any of clauses 7-9, wherein the first self-alignment pattern comprises a hydrophilic material, and the corresponding second self-alignment pattern comprises a hydrophobic material, or vice versa.13. The method of clause 12, further comprising causing the self-alignment with a fluid layer between the first semiconductor substrate and the second semiconductor substrate.14. The method of any of clauses 7-9, wherein the first self-alignment pattern and the corresponding second self-alignment pattern comprise electrically conductive pads.15. The method of clause 14, further comprising applying a potential difference across the electrically conductive pads to form a capacitor and provide the self-alignment.16. The method of any of clauses 7-9, wherein the first self-alignment pattern comprises a donor mechanical structure, and the corresponding second self-alignment pattern comprises an acceptor mechanical structure.17. The method of clause 16, wherein the donor mechanical structure and the acceptor mechanical structure comprise corresponding studs and recesses, the corresponding studs and / or recesses having generally cylindrical, triangular, rectangular, domed and / or trapezoidal shapes.18. The method of any of clauses 1-6, wherein the self-alignment is caused by: a first self-alignment pattern on an acceptor location facing surface of a holder or carrier of a first semiconductor substrate, and a corresponding second self-alignment pattern, on a first semiconductor substrate facing surface of a holder or carrier of a second semiconductor substrate, to interact with the first self-alignment pattern.19. The method of clause 18, wherein: the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric; the first self-alignment pattern and the corresponding second self-alignment pattern are electrostatically activated; the first self-alignment pattern is positively charged, and the corresponding second self-alignment pattern is negatively charged, or vice versa; the first self-alignment pattern comprises a hydrophilic material, and the corresponding second self-alignment pattern comprises a hydrophobic material, or vice versa; the first self-alignment pattern and the corresponding second self-alignment pattern comprise electrically conductive pads; and / or the first self-alignment pattern comprises a donor mechanical structure, and the corresponding second self-alignment pattern comprises an acceptor mechanical structure.20. The method of any of the preceding clauses, wherein: a first semiconductor substrate comprises a die and a second semiconductor substrate comprises an acceptor location; movement of the semiconductor die toward the acceptor location is caused by applying radiation to, or near, the semiconductor die to cause transfer of the semiconductor die toward the acceptor location, and the semiconductor die is bonded to the acceptor location by intermolecular bonding.21. The method of clause 20, wherein the semiconductor die is adhered to a carrier structure at atime of application of the radiation.22. The method of clause 20 or clause 21, further comprising heating the semiconductor die in contact with the acceptor location to cause or improve electrical contact between the semiconductor die and the acceptor location.23. The method of any of the preceding clauses, wherein a plurality of semiconductor dies for transfer are provided to a carrier structure.24. The method of clause 23, wherein radiation is provided to cause transfer of two or more dies of the plurality of semiconductor dies at a substantially same time, wherein self-alignment is maintained during transfer for each of the two or more dies.25. The method of clause 23 or clause 24, further comprising providing relative movement between the carrier structure and an acceptor location to enable transferring of a first die toward a first part of the acceptor location and transferring of a second die toward a second part of the acceptor location, the transferring of the first die and the transferring of the second die being separate in time, with self-alignment maintained during transfer for each of the first die and the second die.26. A system for bonding semiconductor substrates, the system comprising: a structure configured to cause self-alignment to control a relative position between the semiconductor substrates during the bonding.27. The system of clause 26, wherein the semiconductor substrates comprise a semiconductor die or a semiconductor wafer, such that bonding comprises die to wafer bonding, die to die bonding, or wafer to wafer bonding.28. The system of any of the preceding clauses, wherein: one of the semiconductor substrates comprises a semiconductor die, and another one of the semiconductor substrates comprises an acceptor location; and the structure causes self-alignment of the semiconductor die relative to the acceptor location during transfer of the semiconductor die to the acceptor location for bonding.29. The system of clause 28, wherein the self-alignment is maintained in a period between release of the semiconductor die and bonding of the semiconductor die to the acceptor location.30. The system of clause 28 or clause 29, wherein the acceptor location is on a semiconductor wafer.31. The system of any of clauses 28-30, wherein the acceptor location comprises a second semiconductor die.32. The system of any of the preceding clauses, wherein the structure comprises: a first selfalignment pattern on an acceptor location facing surface of a first semiconductor substrate, and a corresponding second self-alignment pattern, on a first semiconductor substrate facing surface of a second semiconductor substrate, at the acceptor location, to interact with the first self-alignment pattern.33. The system of clause 32, wherein the first self-alignment pattern and the corresponding second self-alignment pattern each repeats in two dimensions, or comprises separate pattern portionsfor the two dimensions such that an exact negative of a pattern is not needed for self-alignment.34. The system of clause 32 or clause 33, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric.35. The system of any of clauses 32-34, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are electrostatically activated.36. The system of clause 35, wherein the first self-alignment pattern is positively charged, and the corresponding second self-alignment pattern is negatively charged, or vice versa.37. The system of any of clauses 32-34, wherein the first self-alignment pattern comprises a hydrophilic material, and the corresponding second self-alignment pattern comprises a hydrophobic material, or vice versa.38. The system of clause 37, further comprising a fluid layer between the first semiconductor substrate and the second semiconductor substrate.39. The system of any of clauses 32-34, wherein the first self-alignment pattern and the corresponding second self-alignment pattern comprise electrically conductive pads.40. The system of clause 39, wherein a potential difference across the electrically conductive pads forms a capacitor and provides the self-alignment.41. The system of any of clauses 32-34, wherein the first self-alignment pattern comprises a donor mechanical structure, and the corresponding second self-alignment pattern comprises an acceptor mechanical structure.42. The system of clause 41, wherein the donor mechanical structure and the acceptor mechanical structure comprise corresponding studs and recesses, the corresponding studs and / or recesses having generally cylindrical, triangular, rectangular, domed and / or trapezoidal shapes.43. The system of any of clauses 26-31, wherein the structure comprises: a first self-alignment pattern on an acceptor location facing surface of a holder or carrier of a first semiconductor substrate, and a corresponding second self-alignment pattern, on a first semiconductor substrate facing surface of a holder or carrier of a second semiconductor substrate, to interact with the first self-alignment pattern.44. The system of clause 43, wherein: the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric; the first self-alignment pattern and the corresponding second self-alignment pattern are electrostatically activated; the first self-alignment pattern is positively charged, and the corresponding second self-alignment pattern is negatively charged, or vice versa; the first self-alignment pattern comprises a hydrophilic material, and the corresponding second self-alignment pattern comprises a hydrophobic material, or vice versa; the first self-alignment pattern and the corresponding second self-alignment pattern comprise electrically conductive pads; and / or the first self-alignment pattern comprises a donor mechanical structure, and the corresponding second self-alignment pattern comprises an acceptor mechanical structure.45. The system of any of the preceding clauses, wherein: a first semiconductor substratecomprises a die and a second semiconductor substrate comprises an acceptor location; movement of the semiconductor die toward the acceptor location is caused by applying radiation, from a radiation source, to or near the semiconductor die to cause transfer of the semiconductor die toward the acceptor location, and the semiconductor die is bonded to the acceptor location by intermolecular bonding.46. The system of clause 45, wherein the semiconductor die is adhered to a carrier structure at a time of application of the radiation.47. The system of clause 45 or clause 46, further comprising a heater configured for heating the semiconductor die in contact with the acceptor location to cause or improve electrical contact between the semiconductor die and the acceptor location.48. The system of any of the preceding clauses, wherein a plurality of semiconductor dies for transfer are provided to a carrier structure.49. The system of clause 48, further comprising a radiation source configured to provide radiation to cause transfer of two or more dies of the plurality of semiconductor dies at a substantially same time, wherein self-alignment is maintained during transfer for each of the two or more dies.50. The system of clause 48 or clause 49, further comprising one or more processors configured to control relative movement between the carrier structure and an acceptor location to enable transferring of a first die toward a first part of the acceptor location and transferring of a second die toward a second part of the acceptor location, the transferring of the first die and the transferring of the second die being separate in time, with self-alignment maintained during transfer for each of the first die and the second die.

[0129] The term “computer-readable medium” and / or “machine readable medium” as used herein refers to any medium that participates in providing instructions to processor PRO for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as storage device SD. Volatile media include dynamic memory, such as main memory MM. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise bus BS. Transmission media can also take the form of acoustic or radiation waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Computer- readable media can be non-transitory, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH- EPROM, any other memory chip or cartridge. Non-transitory computer readable media can have instructions recorded thereon. The instructions, when executed by a computer, can implement any of the operations described herein. Transitory computer-readable media can include a carrier wave or other propagating electromagnetic signal, for example.

[0130] Various forms of computer readable media may be involved in carrying one or moresequences of one or more instructions to processor PRO for execution. For example, the instructions may initially be borne on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system CS can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled to bus BS can receive the data carried in the infrared signal and place the data on bus BS. Bus BS carries the data to main memory MM, from which processor PRO retrieves and executes the instructions. The instructions received by main memory MM may optionally be stored on storage device SD either before or after execution by processor PRO.

[0131] Computer system CS may also include a communication interface CI coupled to bus BS. Communication interface CI provides a two-way data communication coupling to a network link NDL that is connected to a local network LAN. For example, communication interface CI may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface CI may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface CI sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0132] Network link NDL typically provides data communication through one or more networks to other data devices. For example, network link NDL may provide a connection through local network LAN to a host computer HC. This can include data communication services provided through the worldwide packet data communication network, now commonly referred to as the “Internet” INT. Local network LAN (Internet) may use electrical, electromagnetic, or optical signals that carry digital data streams. The signals through the various networks and the signals on network data link NDL and through communication interface CI, which carry the digital data to and from computer system CS, are exemplary forms of carrier waves transporting the information.

[0133] Computer system CS can send messages and receive data, including program code, through the network(s), network data link NDL, and communication interface CL In the Internet example, host computer HC might transmit a requested code for an application program through Internet INT, network data link NDL, local network LAN, and communication interface CL One such downloaded application may provide all or part of a method described herein, for example. The received code may be executed by processor PRO as it is received, and / or stored in storage device SD, or other nonvolatile storage for later execution. In this manner, computer system CS may obtain application code in the form of a carrier wave.

[0134] While the concepts disclosed herein may be used for manufacturing with a substrate such as a silicon wafer, it shall be understood that the disclosed concepts may be used with any type of manufacturing system (e.g., those used for manufacturing on substrates other than silicon wafers).

[0135] In addition, the combination and sub -combinations of disclosed elements may comprise separate embodiments. For example, one or more of the operations described above may be included in separate embodiments, or they may be included together in the same embodiment.

[0136] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made as described without departing from the scope of the claims set out below.

Claims

CLAIMS1. A method for bonding semiconductor substrates, the method comprising: causing self-alignment to control a relative position between the semiconductor substrates during the bonding.

2. The method of claim 1, wherein the semiconductor substrates comprise a semiconductor die or a semiconductor wafer, such that bonding comprises die to wafer bonding, die to die bonding, or wafer to wafer bonding.

3. The method of claim 1, wherein: one of the semiconductor substrates comprises a semiconductor die, and another one of the semiconductor substrates comprises an acceptor location; and the method comprises causing self-alignment of the semiconductor die relative to the acceptor location during transfer of the semiconductor die to the acceptor location for bonding.

4. The method of claim 3, wherein the self-alignment is maintained in a period between release of the semiconductor die and bonding of the semiconductor die to the acceptor location.

5. The method of claim 3, wherein the acceptor location is on a semiconductor wafer.

6. The method of claim 3, wherein the acceptor location comprises a second semiconductor die.

7. The method of claim 1, wherein the self-alignment is caused by: a first self-alignment pattern on an acceptor location facing surface of a first semiconductor substrate, and a corresponding second self-alignment pattern, on a first semiconductor substrate facing surface of a second semiconductor substrate, at the acceptor location, to interact with the first selfalignment pattern.

8. The method of claim 7, wherein the first self-alignment pattern and the corresponding second self-alignment pattern each repeats in two dimensions, or comprises separate pattern portions for the two dimensions such that an exact negative of a pattern is not needed for self-alignment.

9. The method of claim 7, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are mirror symmetric.

10. The method of claim 7, wherein the first self-alignment pattern and the corresponding second self-alignment pattern are electrostatically activated.

11. The method of claim 10, wherein the first self-alignment pattern is positively charged, and the corresponding second self-alignment pattern is negatively charged, or vice versa.

12. The method of claim 7, wherein the first self-alignment pattern comprises a hydrophilic material, and the corresponding second self-alignment pattern comprises a hydrophobic material, or vice versa.

13. The method of claim 12, further comprising causing the self-alignment with a fluid layer between the first semiconductor substrate and the second semiconductor substrate.

14. The method of claim 7, wherein the first self-alignment pattern and the corresponding second self-alignment pattern comprise electrically conductive pads.

15. A system for bonding semiconductor substrates, the system comprising: a structure configured to cause self-alignment to control a relative position between the semiconductor substrates during the bonding.

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