Method for encapsulating spaced-apart chips with locally curable material, its production and housing

Abstract

A method for processing chips (100), the method comprising: • encapsulating (202) spaced-apart chips (100) with an encapsulating agent (106) comprising a locally curable material; and • separating (204) the encapsulated chips (100) with the encapsulating agent (106) at the uncured other sections of the encapsulating agent (106) into a plurality of encapsulated chip sections (108) by selectively locally curing sections of the encapsulating agent (106) covering at least one section of the chips (100), without curing other sections of the encapsulating agent (106) away from the encapsulated chip sections (108).

Description

BACKGROUND OF THE INVENTIONField of the InventionThe present invention relates to a method of processing chips and to a package.Prior ArtThe housings can be encapsulated electronic chips, the electrical connections of which protrude from the encapsulation and can be connected to an electronic periphery. Prior to packaging, a semiconductor wafer is separated into a plurality of electronic chips. During and / or after the separation of the wafer into the individual electronic chips, the electronic chips of the wafer can be spatially expanded on an adhesive tape, so that the separation and removal of the individual chips is simplified.JP 2016-146 413 A discloses a method for processing chips, comprising steps of applying an adhesive layer comprising a locally curable material to the chips spaced apart from each other; and separating the chips into a plurality of chip portions by selectively locally curing portions of the adhesive layer without curing other portions of the adhesive layer.U.S. Pat. No. 8,563,358 B2 discloses a method for processing chips with a step for self-aligning embedding of the chips, wherein a UV-curing filler is irradiated at a gap next to a chip.US 2006 / 0 115 925 A1 discloses a method for processing chips with a step for curing a filler material at locations located between the chips.Summary of the InventionIt may be necessary to encapsulate chips efficiently.According to an exemplary embodiment, there is provided a method of processing chips, the method comprising encapsulating spaced apart chips with an encapsulant comprising a locally curable material, and separating the encapsulated chips with the encapsulant at the uncured other portions of the encapsulant into a plurality of encapsulated chip portions by selectively locally curing portions of the encapsulant covering at least a portion of the chips without curing other portions of the encapsulant away from the encapsulated chip portions.According to another exemplary embodiment, a package is provided that includes a chip and an encapsulant encapsulating a portion of the chip and including a locally cured material and a means for locally curing the locally cured material. The locally cured material is obtained by locally curing a locally curable material by irradiation with electromagnetic radiation, in particular ultraviolet electromagnetic radiation, wherein the encapsulant encapsulates sidewalls and only a main surface of the chip that are locally cured.According to an exemplary embodiment, an architecture for manufacturing packages includes encapsulating an array of spaced apart chips by covering the chips with a locally curable encapsulant, i.e., with an uncured encapsulating material. Thereafter, the encapsulated chips may be separated into individually encapsulated chip portions by locally curing only portions of the encapsulant covering and at least partially surrounding the chips. Advantageously, other portions of the uncured encapsulant between adjacent encapsulated chip portions are not cured, such that the corresponding encapsulant selectively remains uncured between the adjacent chip portions. Consequently, the uncured encapsulation material between adjacent encapsulated chip portions may remain uncured, while the encapsulation material of the encapsulated chip portions may be cured. Thus, it may be easily possible to separate the encapsulated chip portions from each other at the intentionally mechanically weak, unstable and uncured encapsulation portions away from the encapsulated chip portions. This may significantly simplify a separation process compared to conventional approaches in which cured encapsulation material is cut or sawn through. In particular, this also makes it possible to dispense with a complicated pick-and-place method, in which singulated chips are individually removed, since the described separation method can enable simple collection of separated encapsulated chip portions in a container or the like, for example if the separated encapsulated chip portions drop downward under the influence of gravity, while they separate from one another automatically at the selectively uncured and thus mechanically weak encapsulation interfaces lying therebetween. Therefore, it may be possible to cure only the encapsulation material around the chips, but not between the chips. This may make the sawing of the chips and a pick-and-place method superfluous.Advantageously, an encapsulated chip section thus obtained can be used directly as a finished package (or optionally be post-processed). In this way, a very simple housing can also be produced in a highly efficient manner, which in particular does not require a chip carrier and does not require an additional encapsulation process. The encapsulant of such a package may further contain an active agent, for example a photoinitiator, used for locally curing the locally cured material. In descriptive terms, such a means may be a fingerprint of the manufacturing process described above.DESCRIPTION OF FURTHER EXEMPLARY EMBODIMENTSFurther exemplary embodiments of the method and of the housing are explained below.In the context of the present application, the term "chip" (or electronic chip or electronic component) may particularly denote a bare chip, i.e. an unpackaged (e.g. unmolded) chip of a processed semiconductor, e.g. a singulated piece of a semiconductor wafer. However, a semiconductor chip may also be an already packaged (for example cast or laminated) chip. One or more integrated circuit elements (such as a MEMS, a diode, a transistor, etc.) may be formed in the semiconductor chip. Such a semiconductor chip can be provided with a metallization, in particular with one or more pads. The chip may be embodied, for example, as a power semiconductor chip, active electronic component (for example transistor), passive electronic component (for example capacitance or inductance or ohmic resistance), sensor (for example microphone, light sensor or gas sensor), actuator (for example loudspeaker) or microelectromechanical system (MEMS). Semiconductor chips realized according to example embodiments may be manufactured in silicon technology, gallium nitride technology, silicon carbide technology, etc., for example.In the context of the present application, the term "spaced apart chips" may particularly refer to an array of chips (e.g., in rows and columns) that are laterally spaced apart such that the sidewalls of adjacent chips are laterally displaced. The mutual spacing between the chips can be effected along two mutually perpendicular directions within a common plane or else only along one direction.In the context of the present application, the term "encapsulant" may particularly denote a substantially electrically insulating material configured to surround at least a portion of a chip to provide mechanical protection, electrical insulation and optionally a contribution to heat dissipation during operation. In particular, the encapsulation agent may comprise a resin. The encapsulant may for example comprise a matrix of selectively curable material and optionally filler particles embedded therein. The filler particles can be used, for example, to adjust the properties of the encapsulant. It is also possible for the encapsulation agent to be a selectively curable molding, potting or molding compound. The encapsulant may be manufactured based on a photo tape or an epoxy paste, for example.In the context of the present application, the term "locally curable material" may particularly refer to an encapsulating material that may be processed such that only a local portion thereof is cured, while a remaining portion thereof may remain uncured. The local curing of such an encapsulation material can be effected, for example, by the spatially dependent application of a curing trigger, such as the local application of heat or the local irradiation with electromagnetic radiation (such as a laser beam or a beam with ultraviolet radiation).In the context of the present application, the term "locally cured material" may particularly refer to encapsulation material already cured by the local application of a curing trigger such as electromagnetic radiation or heat. A locally cured material may have already completed, for example, a crosslinking or polymerization reaction of its resin material. A means for locally curing the previously curable and now cured material may still be present in the locally cured material.In the context of the present application, the term "local curing" may particularly denote the process for carrying out curing of a curable encapsulation material selectively and only in a partial region thereof. The spatial area of local curing of an encapsulant may be selected by the locally dependent application of a curing trigger to only a portion of the encapsulant. Such a curing trigger can only act on a specific section of the encapsulation material and trigger curing thereof only where the encapsulation material is struck by the curing trigger.In the context of the present application, the term "means for local curing of locally curable encapsulation material" may particularly denote a chemical substance, for example an additive of a resin-based encapsulation agent, which promotes, catalyzes or performs a curing process of the encapsulation agent upon exposure to a curing trigger such as ultraviolet radiation (or heat or electromagnetic radiation of another suitable wavelength range). In particular, the agent can be a photoinitiator which initiates a photo-based curing of the encapsulation agent, in particular of the resin. Such an active ingredient may initiate or promote, for example, the polymerization or cross-linking of previously uncured resin, such as epoxy resin. A photoinitiator may be, for example, a molecule that generates reactive species (e.g., free radicals, cations, or anions) when exposed to radiation (especially ultraviolet or visible light). Synthetic photoinitiators can be used in photopolymers, the latter being capable of forming at least a portion of the encapsulant resin. A photopolymer may be referred to as a light activated resin, i.e., a polymer that changes properties when exposed to light, preferably in the ultraviolet or visible region of the electromagnetic spectrum. These changes can result in curing of the material due to crosslinking upon exposure to light. A photoinitiator can generate reactive species in a variety of ways, including photodissociation and electron transfer.In the context of the present application, the term "encapsulated chip portion" may particularly refer to a device or element comprising one or more chips at least partially encapsulated by an encapsulant. Such an encapsulated chip portion may be used, for example, directly as a simple-manufactured package or may be further processed to form a more complex package.In the context of the present application, the term "package" may particularly denote an electronic component that may include one or more chips that may be at least partially encapsulated by an encapsulant. For example, many housings may be simultaneously manufactured as a batch before being separated into individual housings. A package may be formed as the aforementioned encapsulated chip portion or may include one or more additional elements such as a carrier and / or another encapsulant.In one embodiment, the local curing comprises the selective irradiation, in particular using a mask, of the portions of the encapsulation agent by irradiation with curing electromagnetic radiation, in particular ultraviolet (UV) electromagnetic radiation, without the other portions of the encapsulation agent being irradiated with the curing electromagnetic radiation. Advantageously, an irradiation pattern in which only a portion of uncured encapsulant is applied to the spaced apart dies can accurately determine which portions of uncured encapsulant are cured and which portions are not. This selective irradiation may be performed in accordance with a mask design defining irradiation transparent and irradiation non-transparent portions. Alternatively to a mask, a spatially limited electromagnetic beam (e.g., a UV laser beam) may also be provided that travels only over the portions of an array of chips that are to be selectively cured. Then only those regions of the encapsulation agent which are struck by the curing radiation are cured. Curing of the encapsulation material may be achieved by UV irradiation.In one embodiment, the method includes washing the uncured portions of the encapsulant other than the encapsulated chip portions. More specifically, the uncured portion may be washed away, for example, by a developing agent. A suitable developing agent may be an organic solvent such as propylene carbonate, gamma-butyrolactone, etc.In an embodiment, the encapsulant may be formed by applying a solid encapsulation layer on the spaced apart chips or by coating the spaced apart chips with an encapsulation liquid. A solid encapsulation layer may be formed, for example, by one or more sheets or films of curable encapsulation material applied, preferably laminated, to the arrangement of the chips spaced apart from one another. It should be ensured that such a solid encapsulation layer is not completely cured by the application process. Alternatively, the cured encapsulation layer can also be applied by coating the arrangement of the mutual chips with a flowable, viscous or liquid uncured encapsulation agent. The latter can be applied, for example, by spin coating. A spatially dependent, selective curing of portions of the encapsulation material covering the chips may preferably take place after the layer of encapsulation material has been applied to the chips. However, it is also possible to carry out the curing partially or entirely during the application, for example by selectively applying curing-triggering heat and / or mechanical pressure only to the regions of the uncured encapsulation layer covering the chips, while intermediate regions of the encapsulation agent remain uncured.The method of the present invention comprises separating the encapsulated chip portions from each other at the uncured other portions of the encapsulant. When separating encapsulated chip portions, which serve in particular as finished housings, at uncured and thus mechanically unstable or soft intermediate regions of the encapsulant between cured chip cover regions of the encapsulant, the encapsulation process can be carried out with very low separating forces between adjacent encapsulated chip portions. Time-consuming separating methods for separating housings, such as sawing or laser cutting by the cured encapsulation, can thus be advantageously omitted. In contrast, the cured encapsulated chip portions can be separated from each other by simply pulling or shaking the encapsulated chip portions, preferably automatically solely by gravity. This can considerably simplify and speed up the process of separating a housing.In one embodiment, the method includes expanding an expansion band on which the chips of a common wafer are arranged to thereby space the chips apart from each other. In the context of the present application, the term "wafer" may particularly denote a semiconductor substrate that has been processed to form a plurality of integrated circuit elements in an active region of the wafer and that may already be singulated into a plurality of separate chips during expansion according to an example embodiment. A wafer may have the shape of a slice, for example, and may have a matrix-like arrangement of chips in rows and columns. It is possible for a wafer to have a circular geometry or a polygonal geometry (such as a rectangular geometry or a triangular geometry). By expanding a wafer on a stretchable expansion ribbon, the chips may preferably be spaced apart along the entire periphery of the wafer. This may form a suitable basis for the subsequent application of an uncured encapsulation layer to all common, spaced apart chips.In one embodiment, the method includes encapsulating the chips on the expanded expansion band with the encapsulant. For example, an encapsulation layer can be applied to all chips, while the chips expanded from one another are still arranged on the expanded expansion band, which also serves as a support on the underside during the encapsulation. This can further simplify the manufacturing process and increase its yield.In one embodiment, the method comprises expanding the expansion band, such that the chips of the wafer are spaced apart from one another in two spatial directions of a plane of the expansion band perpendicular to one another. Consequently, for example, rectangular parallelepiped chips can be separated from adjacent chips along all four side walls. This may allow a completely circumferential encapsulation of the chips. The expansion band can be stretched, for example, such that the chips of the wafer are at a distance of 20 μm to 150 μm from one another. This leads to the mikrobability of encapsulated chip portions with reliable sidewall-coated chips and at the same time ensures a well-defined separation of the chips and the encapsulated chip portions by uncured encapsulation intermediate regions.In one embodiment, the method comprises attaching the still integral wafer to a dicing tape and subsequently dicing the chips from the previously integral wafer. When arranged on the separating tape, the individual chips can be separated from the wafer composite, for example by mechanical separation or by laser separation. Next, adjacent chips can be arranged next to one another and in particular with mutual contact.In one embodiment, the method includes connecting the separated chips to the expansion band and then removing the separation band. While the dicing tape may be optimized as a robust carrier for dicing wafers, the expansion tape may have tensile properties to space the chips apart. Thus, after slicing the wafers and before expansion, replacement of the ribbon can be performed.In one embodiment, the method comprises applying a release layer on the encapsulant. A release layer may be a layer of a material that can retain the chips (e.g., in a tacky manner) before releasing the chips from the release layer. One such trigger for detachment of the chips from the detachment layer may be a change in environmental conditions to transition the detachment layer from a chip holding configuration to a chip releasing configuration. In particular, the triggering of the detachment of the chips from the detachment layer can be effected by supplying heat which converts the detachment layer from an adhesive configuration into a non-adhesive configuration or a configuration which is less adhesive.In one embodiment, the method includes releasing the encapsulated chip portions from the release layer. Prior to releasing the encapsulated chip portions from the release layer, an expansion tape that may have been previously used to expand chips separated from a wafer bond may be removed from the encapsulated chips. Selectively releasing the encapsulated chip portions from the release layer may then complete the process of chip encapsulation and dicing.In one embodiment, the method comprises a treatment of the detachment layer and / or the encapsulation agent, in particular by supplying heat, in order to promote the detachment of the encapsulated chip sections from the detachment layer. Prior to detaching the encapsulated chip portions from the detachment layer, the detachment layer may exert an adhesive holding force on the encapsulated portions. By heating the detachment layer, this holding force can be significantly reduced or even canceled, so that the encapsulated chip sections can easily be removed from the detachment layer. In other embodiments, the non-adhesion of the detachment layer can be achieved by a measure other than heating, for example by irradiation with corresponding electromagnetic radiation.In one embodiment, the method comprises collecting the encapsulated chip portions which are automatically detached from the detachment layer, in particular by gravity. In such a configuration, the encapsulated chip portions attached to the originally adhesive release layer may be located at a bottom of the release layer. When the encapsulated chip portions are arranged face-down on the release layer, a triggered conversion of the release layer from an adhesive configuration into a non-adhesive configuration or only a weakly adhesive configuration results in an automatic release of the encapsulated chip portions from the release layer that is no longer strongly adhesive, so that the shrinkage holding force in combination with the force of gravity forces the encapsulated chip portions to leave the release layer and to fall downward. Thus, a very simple possibility for separating and collecting the encapsulated chip portions or packages may be provided.It may thus be possible to peel off all encapsulated chip portions under gravity in a common process by reducing an adhesion force of the peeling layer. As mentioned above, the release layer can be converted from an adhesive to a non-adhesive configuration by application of heat. Depending on the properties and configuration of the release layer, another trigger for loss of adhesive force may also be used, for example, cooling, irradiation with electromagnetic radiation causing loss of adhesive force, etc.In the case of the present invention, the locally cured material of the case is obtained by locally curing a locally curable material by irradiation with electromagnetic radiation, particularly ultraviolet electromagnetic radiation. A corresponding agent which has promoted curing may still be present in the final encapsulant of the housing.In particular, the locally cured material may contain a cured polymer and a photoinitiator as active ingredient. The photoinitiator may be configured to promote the curing of an initially uncured polymer to thereby form the cured polymer when irradiated with electromagnetic radiation, particularly ultraviolet electromagnetic radiation.In one embodiment, the encapsulant comprises a photo-imaging polymer. A photoimager polymer or photopolymer may be referred to as a light activated resin. Such a resin may be a polymer which changes its properties when exposed to light, preferably in the ultraviolet or visible region of the electromagnetic spectrum. Such a photoimager polymer may be converted from an uncured state to a cured state by electromagnetic radiation and a suitable means for locally curing a photoimager polymer. Changes in the structural and chemical properties of a photoimager polymer can be brought about by chromophores already having a polymer subunit and / or from the outside by addition of photosensitive molecules or other suitable means. A photoimager polymer may contain a mixture of multifunctional monomers and oligomers depending on the intended functional properties of the encapsulant. Photopolymers can cure by crosslinking oligomers upon irradiation with light of a suitable wavelength to form a network polymer. More specifically, the result of photo-curing may be the formation of a thermoset network of polymers.In the package of the present invention, the encapsulant encapsulates the sidewalls and only one major surface of the die that are locally cured. In particular, all four side walls of the respective chip may be completely covered with the encapsulation material. In addition, one of the two opposing main surfaces can also be covered with the encapsulation material. Only one main surface of the chip may then remain exposed beyond the encapsulant. More specifically, five of six surfaces of the chip may be completely covered with the encapsulation material. The main surface of the chip not covered by the encapsulation material may include one or more exposed chip pads that may be used for electrically connecting the package to an electronic periphery. For example, the encapsulated chip portion or package may be mounted on a mounting base, such as a printed circuit board, such that the plurality of exposed pads may be electrically coupled to one or more electrically conductive pads and / or wiring elements of the mounting base.In an embodiment, the thickness of the encapsulant on at least a portion of the sidewalls and / or on the encapsulated main surface of the chip is in a range of 10 μm to 75 μm. Consequently, very compact housings may be provided, which nevertheless have a reliable side wall cover with encapsulation material. This combines a compact design with high electrical and mechanical reliability.In an embodiment, the chip comprises at least one of the following components: a diode chip and a passive electronic component. In the form of a diode chip, a diode can be monolithically integrated into a semiconductor substrate. A passive electronic component may be, for example, a capacitance, an inductance or an ohmic resistance, which are manufactured in chip technology.In an embodiment, the chip comprises at least one pad exposed at a main surface of the chip exposed with respect to the encapsulant. For example, one or more chip pads may be formed on only one of the two opposing main surfaces of the chip to connect the package to an electronic periphery. Such a chip may be oriented front side down, for example, with the at least one chip pad exposed at the bottom of the package. Alternatively, a chip may have pads on both opposing main surfaces (e.g. in a vertical current flow semiconductor component, e.g. in a field effect transistor chip). In such a configuration, both opposing main surfaces of the chip may be free of encapsulation material.In an embodiment, the chips are power semiconductor chips. One or more integrated circuit elements such as transistors (for example field effect transistors such as metal oxide semiconductor field effect transistors and / or bipolar transistors such as insulated gate bipolar transistors) and / or diodes may be integrated into such a power semiconductor chip. Such integrated circuit elements can be used, for example, for switching purposes. Such another integrated circuit element of a power semiconductor component can be integrated into a half bridge or full bridge, for example. Exemplary applications are automotive applications.The one or more chips may include at least one diode or transistor, in particular an insulated gate bipolar transistor. The one or more electronic chips may be used, for example, as semiconductor chips for power applications, for example in the automobile sector. In an embodiment, at least one semiconductor die may comprise a logic IC or a semiconductor die for RF power applications. In an embodiment, the semiconductor die(s) may be used as one or more sensors or actuators in microelectromechanical systems (MEMS), for example, as pressure sensors or acceleration sensors, as a microphone, as a loudspeaker, etc.A semiconductor substrate, preferably a silicon substrate, can be used as substrate or wafer for the semiconductor chips. Alternatively, a silicon oxide or another insulator substrate can also be provided. It is also possible to use a germanium substrate or a III-V semiconductor material. Example embodiments may be implemented in, for example, GaN or SiC technology.The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings, in which like portions or elements are denoted by like reference numerals.Brief Description of the DrawingsThe accompanying drawings, which are included to provide a further understanding of exemplary embodiments of the invention and form a part of the specification, illustrate exemplary embodiments of the invention.In the drawings: FIG. 1 shows a cross-sectional view of a housing according to an example embodiment. FIG. 2 shows a flow diagram of a method for processing chips of a wafer according to an exemplary embodiment. FIGS. 3-8 show various views of structures obtained when performing a method of processing chips according to an example embodiment.DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTSThe figure in the drawing is schematic and not true to scale.Before exemplary embodiments are described in more detail with reference to the figures, some general considerations will be summarized, on the basis of which exemplary embodiments have been developed.In conventional packaging technology, it may be necessary to remove the dies individually by means of die bonders. Such a conventional approach may result in a limited throughput. In addition, without protection, chipping at the edges of a bare die may occur.According to an exemplary embodiment, a fabrication method includes encapsulating spaced apart dies with an encapsulant including a locally curable material. The encapsulated chip body can then be separated in a very simple manner into chip sections encapsulated in a housing. This can advantageously be effected by a local curing process, in which only portions of the encapsulation agent around the respective chips (or around the respective chip groups) are selectively cured. A locally cured encapsulant around the chips may reliably protect the chips from mechanical impacts and reliably electrically decouple the chips from an environment. In contrast to curing the encapsulation sections directly adjoining the chips, the curing of other encapsulation sections remote from the encapsulated chip sections can be deliberately dispensed with, so that the corresponding intermediate encapsulation sections between the housings can remain uncured. While the selectively cured areas around the chips may be cured by curing, the uncured intermediate areas of the encapsulant may remain uncured. Therefore, the separation of the consolidated and cured encapsulated chip portions from each other may be effected at the non-consolidated and uncured intermediate portions of the encapsulant between the encapsulated chip portions. This can advantageously be carried out without sawing through hardened encapsulation material and thus in a simple and quick manner. In addition, a conventionally complicated pick-and-place method for removing individual chips and placing them at a target location can be dispensed with. Since the cured encapsulated chip portions have soft or uncured intermediate encapsulation material therebetween, the separation may be accomplished by a low separation force or even automatically by the encapsulated chip portions falling apart from each other downward, for example under the influence of gravity.In particular, example embodiments enable high throughput packaging by expanding dice of a scrambled wafer and then depositing a photo-imaging polymeric-type encapsulant. By selective photo-curing of only portions of the encapsulation preform, encapsulated chip portions may be defined which are separated only by weakly bonded, uncured and therefore mechanically unstable encapsulation portions. The individual encapsulated chip sections can be separated with little effort and little force at the mechanically weak, non-solidified and therefore uncured sections of the photoimage-forming polymer-like encapsulant.Moreover, in an exemplary embodiment, a stretchable film may be used to allow spacing between chip edges in a horizontal plane. In other words, this may ensure a sufficient distance between adjacent chips after dicing or etching the wafer. Advantageously, an encapsulation layer in the form of a photopolymer film may be provided as upper and lateral protection layers for the bare dies. Thereafter, a mask may be used to remove an unwanted portion of the polymeric film to separate the encapsulated dies or chips from each other. More specifically, this can be achieved by irradiating only the encapsulated portions around the chips with ultraviolet (UV) radiation for curing, while a mask prevents UV radiation of the encapsulated portions between adjacent encapsulated chips. Consequently, non-irradiated and therefore non-solidified and uncured encapsulation portions can be easily removed, thereby separating the encapsulated chip portions. The encapsulated die portions that are already separated or only weakly bonded by uncured encapsulation portions may then be transferred to a hot laminate tape to prepare a bulk release of the separated and encapsulated die. By heating the release laminate side, the encapsulated chip sections are completely released from the laminate tape. The detached encapsulated chip portions that may already be used as end packages may then be collected for further use.Thus, the selectively cured encapsulant may be used to protect bare silicon dies. In this way, a high throughput packaging process can be provided that can increase or even maximize the efficiency of the end package. This can enable bulk packaging, in particular for passive components. Example embodiments may provide ultra-small protection for bare dies using a simple polymeric film which may then be selectively cured according to a predefined spatial curing pattern.Thus, an example embodiment provides an encapsulation architecture that uses a photo-imaging polymeric film to protect the bare dies. At the same time, an encapsulation and package separation process can be performed highly efficiently.In one embodiment, a wafer may be placed on a stretchable film stretched for the distance between the chips. The stretchable film may be stretched for the edge spacing of the chips after dicing or etching the wafer. A photo-imaging polymeric film may be applied as a preform of an encapsulant. A photoinitiator may be incorporated into the encapsulant. The photoimager polymeric film may encapsulate the chips separated from the wafer. A mask may be used to separate the encapsulated chips without dicing. The separated chips can be loosely packaged. Advantageously, the UV separation can be carried out without mechanically sawing through a cured encapsulant. The batch method described makes it possible to dispense with a single removal of the encapsulated chips. The described concept can enable an efficient large housing.FIG. 1 shows a cross-sectional view of a housing 120 according to an example embodiment.The package 120 of FIG. 1 has a chip 100, for example a semiconductor chip (for example a passive component with an integrated diode). An encapsulant 106 encapsulating a portion of the chip 100 is also provided. The encapsulant 100 has a locally cured material (e.g., polymerized epoxy resin) and a means (e.g., a photoinitiator) for locally curing the locally cured material during a manufacturing process (e.g., upon irradiation with suitable electromagnetic radiation, such as UV light).As shown in detail 150, encapsulant 106 may include, for example, a cured polymer 130 as a locally cured material and a photoinitiator 132 as a means for locally curing the locally cured material.The locally cured material may be obtained by locally curing a locally curable material (e.g., epoxy resin not yet polymerized or not yet fully polymerized) by irradiation with electromagnetic radiation such as ultraviolet electromagnetic radiation. The above-mentioned photoinitiator 132 may be configured to promote curing of an initially uncured polymer (such as the above-mentioned as yet unpolymerized epoxy resin) to thereby form the cured polymer 130 when irradiated with ultraviolet electromagnetic radiation. Therefore, the encapsulant 106 may be prepared using a photo-imaging polymer.As shown in FIG. 1, encapsulant 106 may encapsulate sidewalls 122 and only one main surface 124 of chip 100. As also shown, the chip 100 may include one or more pads 126 exposed at a main surface 128 of the chip 100 exposed with respect to the encapsulant 106. Thus, the main surface 124 may be encapsulated by the encapsulant 106, while the opposite other main surface 128 is exposed beyond the encapsulant 108 to enable electrical connection of the encapsulated chip 100 to an electronic periphery (not shown in FIG. 1 ). For example, the housing 120 shown in FIG. 1 may be mounted on a mounting base (not shown), such as a printed circuit board. Pads on the surface of such a pad may be connected to the chip pads 126.The thickness D of the encapsulant 106 at the sidewalls 122 may be in the range of 10 μm to 75 μm, for example.FIG. 2 shows a flow diagram 200 of a method for processing chips 100 of a wafer (see reference sign 102 in FIG. 3 ) according to an exemplary embodiment. The reference numerals used for the following description of the production method also relate to the embodiment of FIGS. 3 to 8.In block 202, the method includes encapsulating the spaced apart chips 100 with an encapsulant 106 comprising a locally curable material (for further details see FIG. 6 ).Referring to a block 204, the method further includes separating the encapsulated chips 100 with the encapsulant 106 into a plurality of encapsulated chip portions 108 by locally curing selective portions of the encapsulant 106 covering at least a portion of the chips 100 without curing other portions of the encapsulant 106 away from the encapsulated chip portions 108 (for further details see FIGS. 6 to 8 ).FIGS. 3-8 show various views of structures obtained in performing a method of processing chips 100, according to an example embodiment.FIG. 3 shows a top view and a cross-sectional view of a wafer 102 initially comprising a plurality of integrally connected chips 100. Wafer 102 may be, for example, a silicon wafer having a plurality of portions defining chips 100. Each of the chips 100, which are still integrally connected at the outset, has, for example, at least one monolithically integrated circuit element, for example an integrated diode (not illustrated).As seen in the cross-sectional view of FIG. 3, the wafer 102, while still integral, may be mounted on a dicing tape 112. Thereafter, the individual chips 100 may be separated from the previously integral wafer 102 by slicing wafers. This may be done, for example, by slicing or sawing the wafer 102 along dicing lines 152 that may extend in two perpendicular directions through the wafer 102. It is also possible to separate the chips 100 from the wafer 102 by etching or laser processing.In short, the wafer 102 may be mounted on a dicing tape 112 (which may be later removed from the individual chips 100, for example, by irradiation with ultraviolet light) and then may be dicing into the chips 100, for example, by dicing or etching the wafer.As shown in FIG. 4, the dicing chips 100 may then be connected to an expansion tape 104 that may be attached to the chips 100 on a main surface opposite to another main surface disposed on the dicing tape 112. While the dicing tape 112 may be configured to support the wafer 102 and the chips 100 during the chip dicing process described above with reference to FIG. 3, the expansion tape 104 may be made of extensible material that may be used to separate adjacent chips 100 within a horizontal plane. After connecting the expansion band 104 to the chips 100, the dicing band 112 may be removed as shown on the left side of FIG. 4. The left side of FIG. 4 thus shows the transition from the chip connection to the isolation band 112 to the chip connection to the expansion band 104.On the right side of FIG. 4, the expansion band 104 on which the chips 100 of the common wafer 102 are arranged may then be expanded to space the chips 100 mounted thereon from each other. The expansion forces exerted on the expansion band 104 and on the chips 100 during chip expansion are denoted by the reference numeral 154 in FIG. 4. The expansion process can be performed simultaneously or sequentially in two orthogonal directions within a horizontal plane, see also FIG. 5.In FIG. 5, the expansion process according to FIG. 4 is explained in more detail.The top view on the left side of FIG. 5 shows a circular wafer 102 (e.g., having a diameter of 8 inches) mounted on a square expansion band 104 (e.g., having a length and width of 300 mm).The further plan view of FIG. 5, which is represented by the reference numeral 154, shows the expansion of the expansion band 104, such that the chips 100 of the wafer 102 are spaced apart from one another in two perpendicular spatial directions of a plane of the expansion band 104, i.e. within the drawing plane of FIG. 5.As shown in a detail 156, the expansion band 104 can be extended such that the chips 100 of the wafer 102 are spaced apart from one another by a distance d 1 in the horizontal direction and by a distance d 2 in the vertical direction. Both d1and d2may be in a range from 20 μm to 150 μm. For example, if a chip 100 has the dimensions 0.4 mm×0.2 mm, the distances d 1 and d 2 may each be 150 μm.A two-dimensional arrangement of the obtained chips 100 is represented by the reference numeral 158.For the expansion of the chips, the chips 100 can be transferred to the expansion belt 104. Thereafter, the expansion band 100 with the chips 100 thereon may be expanded in two orthogonal directions. The distances d 1, d 2 between the chips can be measured, for example, with a CNC (computerized numerical control) vision measurement system.As shown in FIG. 6, a layer of encapsulant 106 may then be attached to the spaced apart chips 100 on the expansion band 104. In particular, the layer of encapsulant 106 may be attached to the chips 100 and the expansion tape 104 while the latter is still in an expanded state (i.e. still under tension) and the chips 100 are spaced apart from each other by the expansion tape 104.For example, the layer of encapsulant 106 may be a film or sheet of uncured encapsulant material laminated as a solid layer to the chips 100. When applying heat and / or mechanical pressure to the solid layer of encapsulant 106 during lamination, care should be taken that at least a portion, preferably all, of the curable material of encapsulant 106 remains uncured at the end of the lamination process. Alternatively to applying the encapsulant 106 by applying a solid encapsulation layer on the spaced apart chips 100, the encapsulant 106 may also be applied by coating the spaced apart chips 100 and the expansion film 104 with an encapsulant 106 in a flowable, preferably liquid or viscous phase. The application of a flowable encapsulant 106 may be performed by spin coating, for example.As already mentioned, after the chips 100 spaced apart from one another have been encapsulated by the encapsulation means 106, said chips should still consist of a locally curable material. This may ensure that after application of the uncured encapsulant 106, certain areas, locations or locations thereof may be selectively cured, while one or more other certain areas, locations or locations thereof may be selectively uncured and thus remain uncured. Preferably, the encapsulant 106 comprises a photo-imaging polymer that can be selectively and site-dependently cured by irradiation of the photo-imaging polymer with suitable electromagnetic radiation, such as UV light.As shown in FIG. 6, selected curing portions 160 of encapsulant 106 may be selectively cured, while non-curing portions 162 of encapsulant 106 may intentionally remain uncured therebetween. This can be done by selectively irradiating only the curing sections 160 of the encapsulation agent 106 with curing electromagnetic radiation 164, while no curing electromagnetic radiation 164 is irradiated onto the non-curing sections 162. This may be defined, for example, by a suitable mask or by guiding an electromagnetic radiation source generating the curing electromagnetic radiation 164 along a predefined trajectory along the encapsulant 106 and covering only a portion of its surface during the irradiation. The curing electromagnetic radiation 164 can be, for example, ultraviolet light.Therefore, the local curing process may include selectively irradiating the curing portions 160 of the encapsulant 106 by irradiation with curing electromagnetic radiation 164 without irradiating the other non-curing portions 162 of the encapsulant 106 with the curing electromagnetic radiation 164. Only the irradiated and thereby cured portions of the encapsulant 106 are cured.As shown, the spatially dependent selective curing process may be performed only for the curing portions 160 but not for the non-curing portions 162 of the encapsulant 106 on the chips 100, wherein the encapsulant 106 is disposed on the expanded expansion band 104. The expansion band 104 may remain intact during the described selective curing process, which may be performed only by UV radiation. Due to the selective curing process, the curing portions 160 each surrounding a chip 100 may form a solid, cured, cured encapsulant 106. The non-hardening portions 162 therebetween may remain uncured. Consequently, separation of individual encapsulated chip portions 108 (see FIG. 7 ) at the uncured non-curing portions 162 may be easily possible without requiring mechanical sawing. In other words, separation regions between encapsulated chip portions 108 may be defined in the encapsulant 106 in which it is not cured.Thus, as shown in FIG. 6, the encapsulated chips 100 with the encapsulant 106 are separated into a plurality of encapsulated chip portions 108 by selectively curing portions 160 of the encapsulant 106 covering a portion of the chips 100 locally without curing the other non-curing portions 162 of the encapsulant 106 away from the encapsulated chip portions 108, in particular between adjacent encapsulated chip portions 108.As illustrated in FIG. 7, a release layer 110 may then be applied, preferably by lamination, to the main surface of the encapsulant 106 exposed according to FIG. 6, i.e. facing away from the expansion band 104. Thereafter, the expansion band 104 may be removed.In the configuration of FIG. 7, the laminated release layer 110 may adhere to the encapsulant 106 and thereby holds the encapsulated chip portions 108 separated from each other by the mechanically weak non-curing portions 162 of the encapsulant 106.Upon application of heat to the configuration shown and described, the release layer 110 may be converted to a non-stick configuration and is then unable to retain the encapsulated chip portions 108 thereon. This allows the encapsulated chip portions 108 to separate from the release layer 110 and fall down by gravity. The encapsulated chip portions 108 may be separated at the mechanically weak non-solidified or non-hardening portions 162 of the encapsulant 106 when still uncured. In short, the encapsulated chip portions 108 are separated at the non-solidified, non-hardening portions 162 of the encapsulant 106 without the need to mechanically saw through hardened encapsulation material, which thus occurs in a very simple manner. The non-solidified, non-hardening portions 162 of the encapsulant 106 may be washed off, for example, by a developing agent such as propylene carbonate, gamma-butyrolactone, etc.In FIG. 8, the latter process is explained in more detail:As mentioned, the described manufacturing method comprises a thermal detachment of the encapsulated chip portions 108 from the detachment layer 110. The heat promotes the detachment of the encapsulated chip portions 108 from the detachment layer 110, which can no longer stick when heated. As a result, it may be possible to catch the encapsulated chip portions 108 that automatically separate from the release layer 110 by dropping due to gravity. This is identified in FIG. 8 by the reference sign 172.Thus, the encapsulated chip portions 108 may be collected in a container 168, such as a carton. Optionally, a guiding structure 170 may assist in the collection process and promote collection of the detached encapsulated chip portions 108 in the container 168. The guide structure 170 can be designed, for example, as a funnel or conical structure.Advantageously, the detachment process that is jointly triggered for all encapsulated chip sections 108 can lead to a batch or mass release of all encapsulated chip sections 108 in a common process. All encapsulated chip portions 108, which were already previously only weakly connected laterally by the non-curing portions 162 of the encapsulant 106 and are now also only weakly connected horizontally to the heated detachment layer 110, drop downward by gravity. The mentioned peeling operation is triggered by reducing an adhering force of the peeling layer 110 by supplying heat.The collected encapsulated chip portions 108 may be used as easily producible packages 120. Each encapsulated chip portion 108 may include a chip 100 (e.g., a diode chip) encapsulated along its five walls by the encapsulant 106 and exposed at its sixth wall to pads 126 not shown in FIG. 8. In this way, the fabricated packaged, encapsulated chip portions 108 may be adequately protected and electrically isolated by the encapsulant 106, while still being electrically accessible to an electronic periphery. Advantageously, a bulk packaging process can be enabled without the need for tapping. In addition, a pick-and-place method for individually removing the chips 100 from a carrier can also be dispensed with.It should be noted that the term "comprising" does not exclude other elements or features and the "a" or "an" does not exclude a plurality. Also, elements described in connection with various embodiments may be combined. It should also be noted that reference numerals should not be understood as limiting the scope of the claims. Moreover, the scope of application of the present application is not intended to be limited to the particular embodiments of the method, apparatus, manufacture, composition of matter, means, methods, and steps described in the specification. Accordingly, the appended claims are intended to include within their scope such processes, apparatus, methods of manufacture, compositions of matter, means, methods or steps.

Claims

A method of processing chips (100), the method comprising: • encapsulating (202) spaced apart chips (100) with an encapsulant (106) comprising a locally curable material; and • separating (204) the encapsulated chips (100) with the encapsulant (106) at the uncured other portions of the encapsulant (106) into a plurality of encapsulated chip portions (108) by selectively locally curing portions of the encapsulant (106) covering at least a portion of the chips (100) without curing other portions of the encapsulant (106) away from the encapsulated chip portions (108).The method of claim 1, wherein the local curing comprises selectively irradiating, in particular using a mask, portions of the encapsulant (106) by irradiation with curing electromagnetic radiation, in particular ultraviolet electromagnetic radiation, without the other portions of the encapsulant (106) being irradiated with the curing electromagnetic radiation.The method of claim 1 or 2, wherein the method comprises applying the encapsulant (106) by applying a solid encapsulation layer on the spaced apart chips (100) or by coating the spaced apart chips (100) with an encapsulation liquid.The method of any of claims 1 to 3, wherein the method comprises expanding an expansion band (104) on which the chips (100) of a common wafer (102) are disposed to thereby space the chips (100) apart from each other.Method according to Claim 4, having at least one of the following features: wherein the method comprises encapsulating the chips (100) on the expanded expansion band (104) by the encapsulation means (106); wherein the method comprises expanding the expansion band (104) such that the chips (100) of the wafer (102) are spaced apart from one another in two perpendicular spatial directions of a plane of the expansion band (104), wherein the method in particular comprises expanding the expansion band (104) such that the chips (100) of the wafer (102) are spaced apart from one another by a distance (d1, d2) in a range from 20 μm to 150 μm.The method of claim 4 or 5, wherein the method comprises mounting the wafer (102), if still integral, on a dicing tape (112) and subsequently dicing the chips (100) from the previously integral wafer (102).The method of claim 6, wherein the method comprises connecting the separated chips (100) to the expansion band (104) and subsequently removing the separation band (112).The method of any of claims 1 to 7, wherein the method comprises applying a release layer (110) on the encapsulant (106).The method of claim 8, wherein the method comprises releasing the encapsulated chip portions (108) from the release layer (110).The method according to claim 9, comprising at least one of the following features: wherein the method comprises treating the detachment layer (110) and / or the encapsulation agent (106), in particular by supplying heat, in order to promote detachment of the encapsulated chip portions (108) from the detachment layer (110); wherein the method comprises collecting the encapsulated chip portions (108) automatically detached from the detachment layer (110), in particular dropping by gravity; wherein the method comprises detaching all encapsulated chip portions (108) in a common process under gravity and by reducing an adhesion force of the detachment layer (110), in particular by supplying heat.The method of any of claims 1 to 10, comprising at least one of the following features: wherein the encapsulant (106) comprises a photoimager polymer; wherein the method comprises washing the uncured other portions of the encapsulant (106) except the encapsulated chip portions (108).A package (120) comprising: • a chip (100); and • an encapsulant (106) encapsulating a portion of the chip (100) and comprising a locally cured material and a means for locally curing the locally cured material, wherein the locally cured material is obtained by locally curing a locally curable material by irradiation with electromagnetic radiation, in particular ultraviolet electromagnetic radiation, wherein the encapsulant (106) encapsulates sidewalls (122) and only a main surface (124) of the chip (100) that are locally cured.The package (120) of claim 12, wherein the locally cured material comprises a cured polymer (130), and wherein the agent comprises a photoinitiator (132), wherein the photoinitiator (132) is configured to promote curing of an initially uncured polymer to thereby form the cured polymer (130) when irradiated with electromagnetic radiation, particularly ultraviolet electromagnetic radiation.The package (120) of any of claims 12 to 13, wherein the encapsulant (106) comprises a photoimager polymer.The package (120) of any of claims 12 to 14, wherein a thickness (D) of the encapsulant (106) on at least a portion of the sidewalls (122) is in the range of 10 μm to 75 μm.The package (120) of any one of claims 12 to 15, wherein the chip (100) comprises at least one of the group consisting of a diode chip and a passive electronic component.The package (120) of any of claims 12 to 16, wherein the chip (100) comprises at least one pad (126) exposed at a main surface (128) of the chip (100) exposed with respect to the encapsulant (106).

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