WO2024149677A1

WO2024149677A1 - Method for producing a connection means and component of an electronic device with a connection means

Info

Publication number: WO2024149677A1
Application number: PCT/EP2024/050201
Authority: WO
Inventors: Thomas Schwarz
Original assignee: Ams-Osram International Gmbh
Priority date: 2023-01-11
Filing date: 2024-01-05
Publication date: 2024-07-18

Abstract

Methods for producing a connection means (4) of a component (1) of an electronic device (10) are described, comprising: - providing a component base structure (20) for producing at least one component base body (2), wherein the component base structure (20) has a main surface (20A), - providing a particle structure (50) on the main surface (20A), wherein particles (51) of the particle structure (50) comprise in each case a liquid core (52) and a solid shell (53) surrounding the liquid core (52), and the liquid core (52) comprises a solder material (54), and - providing an interlayer structure (60) between the main surface (20A) and the particle structure (50). Moreover, a component with a connection means is described.

Description

METHOD FOR PRODUCING A CONNECTION MEANS AND COMPONENT OF AN ELECTRONIC DEVICE WITH A CONNECTION MEANS

Description

This patent application claims the priority of German patent application 10 2023 100 542 . 1 , the disclosure content of which is hereby incorporated by reference .

A method for producing a connection means of a component of an electronic device is speci fied . For example , the electronic device is an optoelectronic device , which may be a light emitting semiconductor device . Moreover, it is also possible that the electronic device includes an integrated circuit ( also referred to as an IC ) device . In addition, a component of an electronic device comprising a connection means is speci fied . For example , the component may be a carrier or an electronic component like an LED chip or IC chip .

For instance , a solder material like AuSn having a melting point of 280 ° C can be used as a connecting means in case of soldering a silicon based component to a copper based component . At this temperature , thermomechanical stress is induced and can result in vertical and/or hori zontal cracks in the silicon based component . Lower soldering temperatures can be achieved by so-called supercooled solder materials . But as these solder materials so far are provided as pastes , layers produced from these pastes are comparatively thick and have a low thermal conductivity, which has a negative impact on the li fetime and reliability of a device . One obj ect inter alia is to speci fy a method for producing a connection means providing for a highly reliable electronic device . Another obj ect inter alia is to speci fy a component of an electronic device providing for a highly reliable electronic device .

These obj ects are achieved inter alia by the methods and the component according to the independent claims . Further embodiments and further developments of the methods and the component are the subj ect-matter of the dependent claims .

According to at least one embodiment of a method for producing a connection means of a component of an electronic device , the method comprises a step of providing a component base structure for producing at least one component base body, wherein the component base structure has a main surface . The component base body may be a carrier body or a semiconductor body forming a functional and/or physical unit of the component of the electronic device . The component base structure may comprise one component base body or an assembly of a plurality of component base bodies .

According to at least one embodiment or configuration, the at least one component base body comprises a semiconductor body, which includes for example a first semiconductor region, a second semiconductor region and an active region therebetween, wherein the active region is provided for emitting or receiving electromagnetic radiation in the infrared, visible or ultraviolet spectral range . Alternatively or additionally, the semiconductor body may comprise one or more electronic circuits . Materials based on arsenide , phosphide or nitride compound semiconductors , for example , are suitable for the semiconductor regions or single layers of the at least one component base body, which is a semiconductor body . "Based on arsenide , phosphide or nitride compound semiconductors" means in the present context that the semiconductor regions or layers contain Al_nGa_mIni-_n-mAs , Al_nGa_mIni-_n-mP, In_nGai-_nAs_mPi-_m or Al_nGa_mIni-_n-mN, where 0 < n < 1 , 0 < m < 1 and n+m < 1 . This material does not necessarily have to have a mathematically exact composition according to the above formula . Rather, it may have one or more dopants as well as additional constituents that do not substantially change the characteristic physical properties of the AlnGamlnx-n-mAs , Al_nGa_mIni-_n-mP, In_nGai-_nAs_mPi-_m or Al_nGa_mIni-_n-mN material . For simplicity, however, the above formula includes only the essential constituents of the crystal lattice (Al , Ga, In, As or P or N, respectively) , even though these may be partially replaced by small amounts of other substances . Moreover, a suitable material for the semiconductor body comprising one or more electronic circuits is silicon, for example .

According to at least one embodiment or configuration, the at least one component base body comprises a carrier body . The carrier body may comprise a leadframe structure , a ceramics solid body or a printed circuit board .

According to at least one embodiment or configuration, the method comprises a step of providing a particle structure on the main surface of the component base structure , wherein particles of the particle structure comprise in each case a liquid core and a solid shell surrounding the liquid core .

The particles may be nano- and/or micro-particles . The particles may have di f ferent si zes and/or shapes . For example , the particles may have the shape of spheres .

According to at least one embodiment or configuration, the liquid core comprises a metal material , for example a solder material . The solder material may be understood as a fusible metal or metal alloy used to create a permanent bond between the component base body and a further element of the electronic device . In particular, the solder material may be a eutectic system . Suitable solder materials are for example tin or tin solders .

The particles may be of a liquid core-shell configuration at a temperature below a melting point of the solder material of the liquid core , for example at room temperature , which may be achieved by inhibiting liquid-solid phase change below the melting point called undercooling or supercooling . Consequently, the particles are undercooled or supercooled particles .

The advantage of the undercooled or supercooled particles is that soldering is possible at temperatures below the melting point of the solder material . For example , a soldering temperature can be reduced by the undercooled or supercooled particles from 280 ° C to 200 ° C for eutectic AuSn, from 230 ° C to 140 ° C for pure Sn and from 140 ° C to 50 ° C for SnBi . The reduced soldering temperatures lead to reduced thermomechanical stress in the electronic device and hence lead to an increased li fetime and reliability of the electronic device .

According to at least one embodiment or configuration, the solid shell comprises a passivating layer including an inorganic material . The inorganic material may comprise an oxide and/or a nitride .

According to at least one embodiment of a first variant of a method for producing a connection means of a component of an electronic device , the method comprises :

- providing a component base structure for producing at least one component base body, wherein the component base structure has a main surface ,

- providing a particle structure on the main surface , wherein particles of the particle structure comprise in each case a liquid core and a solid shell surrounding the liquid core , and the liquid core comprises a solder material , and

- providing an interlayer structure between the main surface and the particle structure , wherein the interlayer structure is applied on the main surface before the particle structure is provided .

The connection means of at least one component of an electronic device may be composed of at least one part of the particle structure and at least one part of the interlayer structure . For example , the interlayer structure may be patterned in such a way that it comprises , related to a design of the component ( s ) , one or more connection regions for each component , wherein the particles are arranged on the one or more connection regions .

According to at least one embodiment or configuration of the first variant , the step of providing the particle structure includes providing a fluid or molten solder material .

Especially, the solder material is the same material as the one from which the liquid cores of the particles are formed subsequently in a particle formation process . The particle formation process includes undercooling of the fluid or molten solder material as explained above in more detail and creating liquid cores . Moreover, the particle formation process may include forming solid shells , which may comprise or consist of passivating layers as mentioned above , by means of oxidation and/or by layer deposition, for example oxide or nitride layer deposition . The layer deposition may be conducted in an inert atmosphere or a fluid .

For example , the step of providing a fluid or molten solder material includes applying the solder material or constituents of the solder material on the main surface of the component base structure and raising an operating temperature to the melting point of the solder material . The solder material or constituents thereof may be applied on the main surface of the component base structure for example by CVD ( Chemical Vapor Deposition) , DVD ( Physical Vapor Deposition) or plating . These methods allow to thinly apply the solder material , and as a result the particle structure and the connection means may have small thicknesses . For example , the connection means may have a thickness of 10 pm or less , resulting in a thin connection layer having a high thermal conductivity, which increases the li fetime and reliability of the electronic device .

According to at least one embodiment or configuration, the step of providing the particle structure may further comprise providing centres of particle formation where the particles are formed in the particle formation process from the fluid or molten solder material during cooling . In summary, the melting and particle formation process as well as the production of the interlayer structure can be conducted at a process stage where the component base bodies are still arranged in an assembly and have not been singulated yet . And thus , the connection means of a plurality of components can be produced in an assembly, which renders the production process rather ef ficient .

For example , the centres of particle formation are nuclei provided on a side of the solder material facing the interlayer structure or on a side of the solder material facing away from the interlayer structure . It is possible that the nuclei are nano-particles , which for example are formed from a constituent of the solder material . A suitable material for the nuclei is Bi , for example .

Alternatively or additionally, the interlayer structure may comprise holes , for example nano-scale holes , which form the centres of particle formation . Possible methods for forming the holes are lithography, nanoimprint or pinhole deposition .

According to at least one embodiment or configuration, the interlayer structure is an anti-wetting layer to which the solder material has a reduced wetting or adhesion . Hence , the interlayer structure or anti-wetting layer supports the formation of particles during the particle formation process .

According to at least one embodiment or configuration, the interlayer structure is an organic layer or inorganic layer . Suitable organic materials are for example polymers , thermoplastics or thermoset resins . Suitable inorganic materials are for example silicon oxide , silicon nitride , tin oxide or aluminium oxide . The interlayer structure or anti- wetting layer may be applied by spin coating with a small thickness of only a few monolayers .

In the following, embodiments or configurations of a second variant of a method for producing a connection means of a component of an electronic device are speci fied . The second variant di f fers from the first variant in that the particles of the particle structure are provided in a finished state on the main surface of the component base structure .

According to at least one embodiment of a second variant of a method, the method comprises the following steps :

- providing an interlayer structure between the main surface and the particle structure , wherein the interlayer structure is applied on the main surface after the particle structure is provided .

Advantageously, the particles may be fixed on the main surface of the component base structure by means of the interlayer structure . Moreover, a wettable layer structure may be arranged on the main surface between the component base structure and the interlayer structure . The wettable layer structure may improve the adhesion of the particles on the main surface of the component base structure . The wettable layer structure may comprise or consist of a metal material like for example Au, Pt or Pd .

According to at least one embodiment or configuration, the step of providing the particle structure includes applying the particles on the main surface . For example , the particles may be distributed in a solvent , wherein the solvent evaporates after the application on the main surface . For example , the particles may be applied on the main surface by a spin or spray coating process . These methods allow to produce the particle structure with a small thickness and as a result the connection means as well . For example , the connection means may have a thickness of 10 pm or less .

According to at least one embodiment or configuration, the step of providing the interlayer structure includes conformally depositing the interlayer structure on the particles . The interlayer structure may cover the main surface in interspaces between the particles .

The interlayer structure may be an oxide or metal layer . Suitable deposition methods are for example PVD or CVD . In the case of a metal layer, a plating method may be used, too .

According to at least one embodiment or configuration of the first variant of the method or the second variant of the method, the interlayer structure is removed in interspaces between the particles . Suitable methods for removing the interlayer structure are etching methods like dry or wet etching, for example with an 02 plasma .

I f the interlayer structure comprises an electrically conductive material as for example in the case of the second variant and/or has a non-critical thickness of less than 200 nm, for example , the interlayer structure may remain in the interspaces .

According to at least one embodiment or configuration of the first variant of the method or the second variant of the method as mentioned above , a wettable layer structure may be arranged on the main surface between the component base structure and the interlayer structure . In the electronic device , a wettable layer formed from the wettable layer structure may provide for a good adhesion of a solder material on an outer surface of the component base body after releasing the solder material . For example , the wettable layer structure comprises or consists of a metal material like for example Au, Pt or Pd .

Moreover, a layer structure of low dissolubility may be arranged between the component base structure and the wettable layer structure . The layer structure of low dissolubility may comprise or consist of at least one of the following metals : Ni , Pd, Pt .

According to at least one embodiment or configuration of the method according to the first or second variant as mentioned above , an adhesive film like a thermal release tape is arranged on the assembly comprising the component base structure , the particle structure and the interlayer structure arranged therebetween, wherein the adhesive film is arranged on the particle structure and contains a pressure sensitive adhesive in order to protect the shells of the particles especially during singulation . The singulation of the assembly may be conducted after the application of the adhesive film along with the adhesive film . The components may be singulated by a cutting-out process .

Alternatively, the assembly may be trans ferred to a further device structure , for example a chip structure or carrier structure , before singulation, wherein the singulation may be conducted by a li ft-of f process of a common substrate of the assembly, for example .

Further processes like sorting and mounting may be executed after the singulation .

In the following, a component of an electronic device is described, wherein the component can be produced by the di f ferent methods explained above . Hence , all features described in connection with the di f ferent methods apply to the component as well , and vice versa .

According to at least one embodiment of a component of an electronic device , the component comprises :

- a component base body and

- a connection means , wherein the connection means includes :

- a particle layer, wherein particles of the particle layer comprise in each case a liquid core and a solid shell surrounding the liquid core , and the liquid core comprises a solder material , and

- an interlayer between the component base body and the particle layer, wherein the connection means is arranged on an outer surface of the component base body and is provided to form a connection layer by releasing the solder material from the solid shells of the particles at a soldering temperature lower than a melting point of the solder material .

The solder material may be released by breaking the solid shells at the soldering temperature .

The component base body may be a carrier body or a semiconductor body including an active region and/or one or more electronic circuits .

The component may be a carrier comprising the carrier body, which for example comprises or consists of a leadframe , a ceramics substrate or PCB, to which an electronic component may be fixed by means of the connection layer .

Alternatively, the component may be an electronic component , which comprises the semiconductor body and may be fixed to a carrier body by means of the connection layer . The electronic component may be an optoelectronic component , for example a radiation emitting component , or an IC component . Possible optoelectronic components are thin film LED chips , flip chips , miniLEDs , microLEDs , edge-emitting laser diode chips , multi-ridge flip chip laser components and VCSELs .

The particle layer may be formed from the particle structure described along with the di f ferent production methods and thus may correspond to the particle structure especially with respect to its structure and/or material composition . In particular, the particles of the particle layer are undercooled or supercooled particles . This particle layer provides for a reduced soldering temperature , which is lower than the melting point of the solder material . The reduced soldering temperature at which the component is fixed to another element leads to reduced thermo-mechanical stress in the electronic device and hence to an increased li fetime and reliability of the electronic device .

Moreover, the methods for providing the particle structure as discussed above including directly producing the particle structure on the component base structure or providing the particle structure by spin or spray coating allow for small thicknesses and hence for thin film soldering . For example , the connection layer produced in a soldering process may have a thickness of 10 pm or less . A high thermal conductivity and a low thermal resistance can be achieved by this connection layer . This provides , for example , for a high optical output power of a radiation-emitting optoelectronic device .

According to at least one embodiment or configuration, the solder material comprises at least one of the following materials or consists thereof : Sn, Bi , Ag, SnAgCu, SnAg, SnBi , AuSn . Furthermore , the solid shells may comprise or consist of an inorganic material including an oxide , for example SiO2 , and/or a nitride , for example SiN . Concerning further embodiments and configurations of the solder material and the solid shells , reference is made to the explanations in connection with the di f ferent methods .

The interlayer may be formed from the interlayer structure described along with the di f ferent production methods and thus may correspond to the interlayer structure especially with respect to its structure and/or material composition . The interlayer may fix the particles to the outer surface of the component base body and thus may provide for a good adhesion of the particles on the outer surface . The interlayer may contain an inorganic material including an oxide , for example silicon oxide or tin oxide , and/or a nitride , for example silicon nitride , and/or a metal , for example Au . Alternatively or additionally, the interlayer may contain an organic material including a plastic material .

Concerning further embodiments and configurations of the interlayer, reference is made to the explanations in connection with the di f ferent methods .

According to at least one embodiment or configuration, a wettable layer is arranged on the outer surface between the component base body and the interlayer . The wettable layer may be formed from the wettable layer structure described along with the di f ferent production methods and thus may correspond to the wettable layer structure especially with respect to its structure and/or material composition .

Moreover, a layer of low dissolubility may be arranged between the component base body and the wettable layer . The layer of low dissolubility may be formed from the layer structure of low dissolubility described along with the di f ferent production methods and thus may correspond to the layer structure of low dissolubility especially with respect to its structure and/or material composition .

The above described component may be a part of an electronic device . According to at least one embodiment , the electronic device comprises a carrier body and a semiconductor body, which includes an active region and/or one or more electronic circuits and is arranged on the carrier body, wherein the carrier body and the semiconductor body are connected by the connection layer formed from the connection means by a soldering process . The connection layer may comprise residues of the solid shells. Moreover, the connection layer may comprise undestroyed particles.

The component or electronic device is suitable for automotive headlamps, for projection and display devices and high and low power lasers, for example.

Further embodiments and developments of the different methods for producing a connection means of a component of an electronic device as well as of the component and electronic device will become apparent from the exemplary embodiments explained below in conjunction with the Figures.

Figures 1A to IF and 2A to 2F show schematic side views (see the upper Figures indicated by "a") and schematic plan views (see the lower Figures indicated by "b") of exemplary embodiments of a first variant of a method,

Figures 3A to 3E and 4A to 4E show schematic side views (see the upper Figures indicated by "a") and schematic plan views (see the lower Figures indicated by "b") of exemplary embodiments of a second variant of a method,

Figures 5a to 5d show different schematic views of an exemplary embodiment of a component and of an electronic device,

Figures 6 to 11 show schematic side views (see the Figures indicated by "a") and schematic top views (see the Figures indicated by "b") of exemplary embodiments of a component, and Figures 12a to 12d show di f ferent schematic views of an exemplary embodiment of a component and of an electronic device .

Identical , equivalent or equivalently acting elements may be indicated with the same reference numerals in the figures . The figures are schematic illustrations and thus not necessarily true to scale . Comparatively small elements and particularly layer thicknesses can rather be illustrated exaggeratedly large for the purpose of better clari fication .

According to an exemplary embodiment of a first variant of a method for producing a connection means 4 of a component 1 of an electronic device 10 , which may be an optoelectronic device ( see Figures 1A to I F and Figures 5 and 6 ) , the method comprises providing a component base structure 20 for producing at least one component base body 2 ( see Figures 1A- a, 5 and 6 ) , wherein the component base body 2 may be a carrier body or a semiconductor body forming a functional and/or physical unit of the component 1 of the electronic device 10 ( see Figures 5 and 6 ) . The component base structure 20 may comprise one component base body 2 or an assembly of a plurality of component base bodies 2 .

The component base structure 20 provided for producing at least one semiconductor body, for example at least one optoelectronic semiconductor body, may include a first semiconductor layer 21 of a first , for example n- , conductivity type , a second semiconductor layer 23 of a second, for example p- , conductivity type and an active layer 22 therebetween, wherein the active layer 22 is suitable for emitting or receiving electromagnetic radiation in the infrared, visible or ultraviolet spectral range .

Materials based on arsenide , phosphide or nitride compound semiconductors , for example , are suitable for the semiconductor layers 21 , 22 , 23 , wherein, as mentioned above , "based on arsenide , phosphide or nitride compound semiconductors" means in the present context that the semiconductor regions or layers contain AlnGamlnx-n-mAs , Al_nGa_mIni-_n-mP, In_nGai-_nAs_mPi-_m or Al_nGa_mIni-_n-mN, where 0 < n < 1 , 0 < m < 1 and n+m < 1 .

According to at least one embodiment or configuration, the at least one component base body is a carrier body . The component base structure 20 provided for producing at least one carrier body may comprise a leadframe structure , a ceramics solid body or a printed circuit board . Moreover, the at least one component base body may be a semiconductor body with one or more electronic circuits representing an integrated circuit element . And the component base structure 20 may comprise one or an assembly of semiconductor bodies representing in each case an integrated circuit element .

As shown in Figure lA-a, a wettable layer structure 70 is arranged on a main surface 20A of the component base structure 20 . For example , the wettable layer structure 70 comprises or consists of a metal material like for example Au, Pt or Pd . In the electronic device 10 , a wettable layer 7 formed from the wettable layer structure 70 may provide for a good adhesion of a solder material on an outer surface 2A of the component base body 2 after releasing the solder material . Moreover, a layer structure 80 of low dissolubility may be arranged between the component base structure 20 and the wettable layer structure 70 . The layer structure 80 of low dissolubility may comprise or consist of at least one of the following metals : Ni , Pd, Pt .

The method further comprises a step of providing an interlayer structure 60 on the main surface 20A on a side of the wettable layer structure 70 facing away from the component base structure 20 ( see Figure IB-a ) . For example , the interlayer structure 60 is formed as an anti-wetting layer to which a solder material has a reduced wetting or adhesion . Hence , the interlayer structure 60 or anti-wetting layer supports the formation of particles during a particle formation process as described in connection with Figure ID . The interlayer structure 60 may be an organic layer or inorganic layer . Suitable organic materials are for example polymers , thermoplastics or thermoset resins . Suitable inorganic materials are oxides or nitrides , for example silicon oxide , silicon nitride , tin oxide or aluminium oxide . The interlayer structure 60 or anti-wetting layer may be applied by spin coating with a small thickness of only a few monolayers .

The method further comprises a step of applying a solder material 54 or constituents of the solder material 54 on the main surface 20A of the component base structure 20 on a side of the interlayer structure 60 facing away from the component base structure 20 ( see Figure IB-a ) . The solder material 54 may be understood as a fusible metal or metal alloy used to create a permanent bond between the component base body and a further element of the electronic device . In particular, the solder material 54 may be a eutectic system . Suitable solder materials are for example tin or tin solders as mentioned above .

The solder material 54 or constituents thereof may be applied on the main surface 20A for example by CVD ( Chemical Vapor Deposition) , DVD ( Physical Vapor Deposition) or plating . These methods allow to thinly apply the solder material 54 or the constituents of the solder material 54 , and as a result a particle structure 50 ( see Figure ID-a ) and the connection means can have relatively small thicknesses . For example , the connection means may have a thickness of 10 pm or less .

The method may further comprise a step of providing centres of particle formation, which support the formation of particles 50 ( see Figure ID-a ) . The centres of particle formation may be nuclei 100 ( see Figures IC-a and IC-b ) . The nuclei 100 may be deposited on a side of the solder material 54 facing the interlayer structure 60 or on a side of the solder material 54 facing away from the interlayer structure 60 . The nuclei 100 may be deposited by spray coating . It is possible that the nuclei 100 are nano-particles , which for example are formed from a constituent of the solder material 54 . A suitable material for the nuclei 100 is Bi , for example .

The method further comprises a step of heating the solder material 54 and raising an operating temperature to a melting point of the solder material 54 and hence producing a fluid or molten solder material 54 . For example , the melting point of eutectic AuSn is about 280 ° C, that of pure Sn is about 230 ° C, and that of SnBi is about 140 ° C . The steps of applying and heating the solder material 54 precede a particle formation process which includes undercooling or supercooling of the fluid or molten solder material 54 by inhibiting liquid-solid phase change when cooling down the solder material 54 below the melting point to create undercooled or supercooled particles 51 , which each comprise a solid shell 53 and a liquid core 52 surrounded by the solid shell 53 . The particles 51 may be nano- and/or micro-particles . The particles 51 may have di f ferent si zes and/or shapes . For example , the particles 51 may have the shape of spheres . The solid shells 53 may be formed by oxidation and/or by layer deposition, for example by oxide or nitride layer deposition, and hence comprise or consist of a passivating layer including an inorganic material like an oxide and/or a nitride . The layer deposition may be conducted in an inert atmosphere or a fluid .

The melting and particle formation process as well as the production of the interlayer structure 60 can be conducted at a process stage where the component base structure 20 has not been singulated yet . Hence , the connection means 4 ( see Figures 5 and 6 ) , which are formed from the particle structure 50 and the interlayer structure 60 , can be produced in an assembly, which renders the production process rather ef ficient .

The method may further comprise a step of removing the interlayer structure 60 in interspaces 55 between the particles 51 in such a way that the wettable layer 70 is uncovered in the interspaces 55 and may be wetted by the solder material 54 in a soldering process . The patterned interlayer structure 60 comprises a plurality of islands , wherein one particle 51 may be arranged on one island ( see Figure lE-a) . Suitable methods for removing the interlayer structure 60 are etching methods like dry or wet etching, for example with an 02 plasma.

The method may further comprise a step of arranging an adhesive film 110 like a thermal release tape on the assembly comprising the component base structure 20, the particle structure 50 and the interlayer structure 60 arranged therebetween, wherein the adhesive film 110 is arranged on the particle structure 50 on a side facing away from the interlayer structure 60 and may contain a pressure sensitive adhesive in order to protect the shells 53 of the particles 51 especially during singulation.

The singulation of the assembly may be conducted after the application of the adhesive film 110 along with the adhesive film. The components 1 (see Figures 5 and 6) may be singulated by a cutting-out process.

Alternatively, the assembly may be transferred to a further device structure, for example a carrier structure, before singulation, wherein the singulation may be conducted by a lift-off process of a common substrate of the assembly.

Further processes like sorting and mounting may be executed after singulation.

Due to the undercooled or supercooled particles 51, the singulated component (s) can be soldered at temperatures below the melting point of the solder material 54. For example, a soldering temperature can be reduced from about 280°C to 200°C for eutectic AuSn, from about 230°C to 140°C for pure Sn and from about 140°C to 50°C for SnBi . The reduced soldering temperatures lead to reduced thermo-mechanical stress in the electronic device 10 ( see Figures 5 and 6 ) and hence to an increased li fetime and reliability of the electronic device 10 .

In connection with Figures 2A to 2 F, another exemplary embodiment of the first variant of the method is described .

The method may comprise the steps of providing a component base structure 20 , applying a wettable layer structure 70 on a main surface 20A of the component base structure 20 and applying an interlayer structure 60 on the wettable layer structure 70 as described in connection with Figures 1A and IB, for example .

However, as becomes evident from Figures 2B-a and 2B-b, the interlayer structure 60 is formed with holes 61 , for example nano-scale holes , which form centres of particle formation . Moreover, the interlayer structure 60 may be patterned in such a way that it comprises , related to a design of the component ( s ) , one or more connection regions for each component . Possible methods for forming the holes 61 are lithography, nanoimprint or pinhole deposition . The holes 61 can be regularly or randomly arranged in the interlayer structure 60 . Moreover, the holes 61 can have the same or di f ferent si zes .

As shown in Figures 2C to 2D, the method further comprises the steps of providing a solder material 54 on the interlayer structure 60 , undercooling or supercooling the solder material 54 and creating a particle structure 50 comprising a plurality of undercooled or supercooled particles 51 as also described in connection with Figures 1C and ID . The particles 51 are formed at the holes 61 and laterally extend beyond the holes 61 such that they laterally overlap with the interlayer structure 60 . In the context of the present application, " laterally" means , for example , parallel to a main extension plane of the component base structure 20 . In the holes 61 , the particles 51 may be in direct contact with the wettable layer structure 70 . The particles 51 may have di f ferent si zes .

As shown in Figure 2E , the method may further comprise the step of removing the interlayer structure 60 in interspaces 55 between the particles 51 to uncover the wettable layer structure 70 as also described in connection with Figure IE , for example .

As shown in Figure 2 F, the method may further comprise the step of providing an adhesive film 110 on the particle structure 50 to protect the particles 51 during further processing .

In addition, the method may have any of the features , characteristics and advantages mentioned in connection with the further exemplary embodiments .

In connection with Figures 3A to 3E , an exemplary embodiment of a second variant of a method for producing a connection means of a component of an electronic device is described .

The second variant di f fers from the first variant in that the particles are provided in a finished state , that is as supercooled or undercooled particles . As shown in Figure 3A, the method comprises the steps of providing a component base structure 20 and applying a wettable layer structure 70 on a main surface 20A of the component base structure 20 as described in connection with Figure 1A, for example .

As shown in Figure 3B, the method further comprises a step of applying on the main surface 20A particles 51 , which especially are undercooled or supercooled particles and comprise in each case a liquid core 52 and a solid shell 53 surrounding the liquid core 52 , wherein the liquid core 52 comprises a solder material 54 as described in connection with the first variant , for example .

The particles 51 may be distributed in a solvent 56 to reach a lower concentration . For example , the concentration can be made so low that only a monolayer of particles 51 is formed . The solvent 56 may evaporate after application on the main surface 20A.

For example , the particles 51 may be applied on the main surface 20A by spin or spray coating . These methods allow to produce a particle structure 50 ( see Figure 3C-a ) with a small thickness and as a result the connection means as well . Especially, the particles 51 are applied on the wettable layer structure 70 , which improves the adhesion of the particles 51 on the main surface 20A. The wettable layer structure 70 may comprise or consist of a metal material like for example Au, Pt or Pd .

As shown in Figure 3C, the method further comprises a step of providing an interlayer structure 60 , wherein the interlayer structure 60 is applied on the main surface 20A after the particle structure 50 is provided . The interlayer structure 60 is conformally deposited on the particles 51 and covers the wettable layer structure 70 in interspaces 55 between the particles 51 even partially below the particles 51 .

Advantageously, the particles 51 can be fixed on the main surface 20A or on the wettable layer structure 70 by means of the interlayer structure 60 . The interlayer structure 60 may be a metal layer . Suitable deposition methods are for example PVD, CVD or plating .

As shown in Figure 3D, the interlayer structure 60 may be removed in the interspaces 55 between the particles 51 . The patterned interlayer structure 60 may comprise a plurality of islands , wherein one particle 51 is arranged on one island . However, as the interlayer structure 60 may comprise an electrically conductive material , the interlayer structure 60 may remain in the interspaces 55 .

Suitable methods for removing the interlayer structure are etching methods like dry or wet etching, for example with an 02 plasma .

As shown in Figure 3E , the method may further comprise a step of providing an adhesive film 110 on the particle structure 50 as also described in connection with Figure I F, for example .

In addition, the method may have any of the features , characteristics and advantages mentioned in connection with the further exemplary embodiments . In connection with Figures 4A to 4E , another exemplary embodiment of the second variant of the method is described .

The method steps shown in Figures 4A and 4B may correspond to the method steps shown in and discussed in connection with Figures 3A and 3B .

Moreover, as shown in Figure 4C, the method may comprise a step of providing an interlayer structure 60 as discussed in connection with Figure 3C, wherein the interlayer structure 60 is applied on the main surface 20A after the particle structure 50 and is conformally deposited on the particles 51 and covers the wettable layer structure 70 in interspaces 55 between the particles 51 even partially below the particles 51 . Moreover, the particles 51 can be fixed on the main surface 20A or on the wettable layer structure 70 by means of the interlayer structure 60 , too . However, the interlayer structure 60 may be an oxide layer instead of a metal layer . Suitable deposition methods are for example PVD or CVD .

As shown in Figure 4D, the interlayer structure 60 is removed in the interspaces 55 between the particles 51 to uncover the wettable layer structure 70 from the electrically non- conductive interlayer structure 60 in order to provide for an electrical connection between the solder material 54 and a wettable layer 7 of the component 1 ( see Figures 5 and 6 ) when the component 1 is soldered . Suitable methods for removing the interlayer structure 60 are etching methods like dry or wet etching, for example with an 02 plasma . The patterned interlayer structure 60 may comprise a plurality of islands , wherein one particle 51 is arranged on one island . However, i f the interlayer structure 60 has a non-critical thickness of less than 200 nm, for example , the interlayer structure 60 may remain in the interspaces 55 .

As shown in Figure 4E , the method may further comprise a step of providing an adhesive film 110 on the particle structure 50 as also described in connection with Figure I F, for example .

In connection with Figures 5a to 5d, exemplary embodiments of an electronic device , which is an optoelectronic device , and a component thereof are described . The component 1 can be produced by any of the methods described in connection with Figures 1 to 4 . Hence , all features described in connection with the di f ferent methods apply to the component 1 as well , and vice versa .

Figure 5a shows a schematic side view of a component 1 as well as a schematic exploded side view of an electronic device 10 comprising the component 1 before attaching the component 1 to another element 3 . Figure 5b shows a flipped schematic side view of a part of the component 1 shown in Figure 5a in greater detail . Figure 5c shows a schematic top view of the electronic device 10 shown in Figure 5a after attaching the component 1 to the other element 3 . Figure 5d shows a schematic bottom view of the part shown in Figure 5b .

The component 1 comprises a component base body 2 produced from a component base structure 20 as described in connection with Figures 1 to 4 . In particular, the component base body 2 is a semiconductor body comprising a first semiconductor region 21A of a first , for example n- , conductivity type , formed from the first semiconductor layer 21 and thus may correspond to the first semiconductor layer 21 with respect to its layer structure and/or with respect to its material composition as mentioned above . The semiconductor body further comprises a second semiconductor region 23A of a second, for example p- , conductivity type , formed from the second semiconductor layer 23 and thus may correspond to the second semiconductor layer 23 with respect to its layer structure and/or with respect to its material composition as mentioned above . Moreover, the semiconductor body comprises an active region 22A which is formed from the active layer 22 and thus may correspond to the active layer 22 with respect to its layer structure and/or with respect to its material composition as mentioned above . For example , the active region 22A is provided for emitting electromagnetic radiation . Moreover, the component 1 and the electronic device 10 may be radiation emitting devices provided for emitting electromagnetic radiation in the infrared, visible or ultraviolet spectral range , for example . The semiconductor body may be a thin film body from which a growth substrate has been removed at least partly .

The component 1 further comprises a connection means 4 arranged on an outer surface 2A of the component base body 2 , wherein the outer surface 2A may be an outer surface of the second semiconductor region 23A.

A wettable layer 7 and a layer 8 of low dissolubility are arranged between the connection means 4 and the component base body 2 , wherein the wettable layer 7 is arranged on a side of the layer 8 of low dissolubility facing away from the component base body 2 .

The wettable layer 7 is formed from a wettable layer structure 70 as described in connection with Figures 1 to 4 and thus may correspond to the wettable layer structure 70 especially with respect to its structure and/or material composition . Moreover, the layer 8 of low dissolubility is formed from the layer structure 80 of low dissolubility as described in connection with Figures 1 to 4 and thus may correspond to the layer structure 80 of low dissolubility especially with respect to its structure and/or material composition .

The connection means 4 comprises a particle layer 5 formed from a particle structure 50 as described in connection with Figures 1 to 4 and thus corresponds to the particle structure 50 with respect to its layer structure and/or with respect to its material composition as mentioned above . Especially, particles 51 of the particle layer 5 comprise in each case a liquid core 52 and a solid shell 53 surrounding the liquid core 52 , and the liquid core 52 comprises a solder material 54 . Preferably, the particles 51 are undercooled or supercooled particles as explained above in more detail . Moreover, the particles may be nano- and/or micro-particles having diameters d of 5 pm and less , for example . The particles 51 may have di f ferent si zes and/or shapes . For example , the particles 51 have the shape of spheres .

Furthermore , the connection means 4 comprises an interlayer 6 between the component base body 2 and the particle layer 5 , wherein the interlayer 6 is formed from an interlayer structure 60 as described in connection with Figures 1 to 4 and thus may correspond to the interlayer structure 60 with respect to its layer structure and/or with respect to its material composition as mentioned above . The interlayer 6 covers the outer surface 2A at least partly and may be electrically conductive or electrically insulating . I f the interlayer 6 is electrically insulating, it is advantageous i f the interlayer 6 covers the outer surface 2A only partly so that the wettable layer 7 arranged between the component base body 2 and the interlayer 6 may be wetted by the solder material 54 in order to provide an electrical connection when the component 1 is soldered to the element 3 . The element 3 is a carrier body, which comprises a metal leadframe 12 and a molded body 13 , wherein the molded body 13 is formed around the leadframe 12 and comprises a plastics material , for example . However, it is also possible that the carrier body 2 comprises or consists of a ceramics solid body or a printed circuit board .

The component 1 is attached to the other element 3 of the electronic device 10 by the connection means 4 . The solder material 54 can be released by breaking the solid shells 53 at a soldering temperature lower than a melting point of the solder material 54 . The reduced soldering temperature at which the component 1 is fixed to the other element 3 leads to reduced thermo-mechanical stress in the electronic device 10 .

After soldering, the other element 3 or carrier body and the component base body 2 or semiconductor body are connected by a connection layer 11 ( see Figure 5c ) formed from the connection means 4 . The connection layer 11 may comprise residues of the solid shells 53 . Moreover, the connection layer 11 may comprise undestroyed particles 51 . The connection layer 11 may provide for an electrical connection with a first part of the leadframe 12 serving as a first electrical terminal of the electronic device 10 . A contact pad 9 is arranged on a side of the component 1 opposite to the outer surface 2A, which may be connected for example by a wire bond to a second part of the leadframe 12 , serving as a second electrical terminal of the electronic device 10 .

The methods for providing the particle structure 50 as discussed above including directly producing the particle structure 50 on the component base structure 20 or providing the particle structure 50 by spin or spray coating allow for small thicknesses and hence for thin film soldering . For example , the connection layer 11 may have a thickness of 10 pm or less . A high thermal conductivity and a low thermal resistance can be achieved by this connection layer 11 .

In summary, the reduced cracks and increased thermal conductivity provide for an increased li fetime and reliability as well as a high optical output power of the radiation-emitting optoelectronic device 10 .

In connection with Figures 6 to 11 , di f ferent exemplary embodiments of a component 1 are described, wherein the Figures indicated by "a" show schematic side views and the Figures indicated by "b" show schematic top views .

The component 1 may be a thin film LED chip as also described in connection with Figure 5 and may comprise a connection means 4 on a back side 1A and a contact pad 9 on a front side IB of the component 1 ( see Figure 6a ) . By means of the connection means 4 , the component 1 can be connected to another element . Moreover, by the connection means 4 and the contact pad 9 , the component 1 can be connected to electrical terminals of di f ferent polarity of an optoelectronic device .

The component 1 may be a ( sapphire ) flip chip and may comprise two connection means 4 , which are both arranged on a back side 1A of the component 1 ( see Figure 7a ) . The connection means 4 may connect the component 1 to another element and also to electrical terminals of di f ferent polarity of an electronic device .

The component 1 may be a miniLED or microLED and may comprise two connection means 4 , which are both arranged on a back side 1A of the component 1 ( see Figure 8a ) . The connection means 4 may connect the component 1 to another element and also to electrical terminals of di f ferent polarity of an electronic device .

The component 1 may be an edge-emitting laser diode chip and can comprise a connection means 4 on a back side 1A and a ridge element 14 and a contact pad 9 on a front side IB ( see Figure 9a ) . By means of the connection means 4 , the component 1 can be connected to another element . Moreover, by the connection means 4 and the contact pad 9 , the component 1 can be connected to electrical terminals of di f ferent polarity of an electronic device .

The component 1 may be a multi-ridge flip chip laser and can comprise several connection means 4 and ridge elements 14 on a back side 1A ( see Figure 10a ) . The connection means 4 may connect the component 1 to another element and also to electrical terminals of di f ferent polarity of an electronic device . The component 1 may be a VCSEL (Vertical Cavity Surface Emitting Laser ) and can comprise a connection means 4 on a back side 1A and a contact pad 9 on a front side IB of the component 1 ( see Figure I la ) . By means of the connection means 4 , the component 1 can be connected to another element . Moreover, by the connection means 4 and the contact pad 9 , the component 1 can be connected to electrical terminals of di f ferent polarity of an electronic device .

In connection with Figures 12a to 12d, exemplary embodiments of an electronic device 10 , which is an optoelectronic device , and a component 1 thereof are described . The component 1 can be produced by any of the methods described in connection with Figures 1 to 4 . Hence , all features described in connection with the di f ferent methods apply to the component 1 as well , and vice versa .

Figure 12a shows a schematic side view of a component 1 as well as a schematic exploded side view of an electronic device 10 comprising the component 1 before connecting the component 1 with another element 3 ( arrow indicates connecting process ) . Figure 12b shows a schematic side view of a part of the component 1 shown in Figure 12a in greater detail . Figure 12c shows a schematic top view of the electronic device 10 shown in Figure 12a after connecting the component 1 with the other element 3 . Figure 12d shows a schematic bottom view of the part shown in Figure 12b .

The electronic device 10 may be an optoelectronic device , especially a radiation emitting device as described in connection with Figure 5 . However, in the exemplary embodiment of Figure 12 , the connection means 4 is a part of a carrier and is arranged on an outer surface 2A of a component base body 2 , which is a carrier body .

As described in connection with Figure 5 , the carrier body may comprise a metal leadframe 12 and a molded body 13 , which is formed around the leadframe 12 and comprises a plastics material , for example . However, it is also possible that the carrier body comprises or consists of a ceramics solid body or a printed circuit board .

The element 3 , which is connected with the component base body 2 by the connection means 4 or connection layer 11 may be an optoelectronic component comprising a semiconductor body having an active region as described in connection with Figure 5 . The connection means 4 or connection layer 11 has the same features as mentioned in connection with Figure 5 . A wettable layer 7 and layer 8 of low dissolubility are arranged between the component base body 2 and the connection means 4 , wherein the wettable layer 7 is arranged on a side of the layer 8 of low dissolubility facing away from the component base body 2 .

In addition, the component base body 2 or the carrier body, the element 3 or the optoelectronic component and the electronic device 10 may have any of the features , characteristics and advantages mentioned in connection with the further exemplary embodiments , especially in connection with the exemplary embodiments of Figure 5 .

The scope of protection of the invention is not limited to the examples given hereinabove . The invention is embodied in each novel characteristic and each combination of characteristics , which particularly includes every combination of any features which are stated in the claims , even i f this feature or this combination of features is not explicitly stated in the claims or in the examples .

References

1 component

1A back side

IB front side

2 component base body

2A outer surface

3 element

4 connection means

5 particle layer

6 interlayer

7 wettable layer

8 layer of low dissolubility

9 contact pad

10 electronic device

11 connection layer

12 leadframe

13 molded body

14 ridge element

20 component base structure

20A main surface

21 first semiconductor layer

21A first semiconductor region

22 active layer

22A active region

23 second semiconductor layer

23A second semiconductor region

50 particle structure

51 particle

52 core

53 shell 54 solder material

55 interspace

56 solvent

60 interlayer structure 61 hole

70 wettable layer structure

80 layer structure of low dissolubility

100 nuclei

110 adhesive film d diameter

Claims

Claims

1. A method for producing a connection means (4) of a component (1) of an electronic device (10) , the method comprising :

- providing a component base structure (20) for producing at least one component base body (2) , wherein the component base structure (20) has a main surface (20A) ,

- providing a particle structure (50) on the main surface (20A) , wherein particles (51) of the particle structure

(50) comprise in each case a liquid core (52) and a solid shell (53) surrounding the liquid core (52) , and the liquid core (52) comprises a solder material (54) , and

- providing an interlayer structure (60) between the main surface (20A) and the particle structure (50) , wherein the interlayer structure (60) is applied on the main surface (20A) before the particle structure (50) is provided, wherein providing the particle structure (50) includes:

- providing a fluid or molten solder material (54) on the main surface (20A) of the component base structure (20) on a side of the interlayer structure 60 facing away from the component base structure 20, and

- providing centres of particle formation where the particles

(51) are formed in a particle formation process from the fluid or molten solder material (54) during cooling.

2. The method according to claim 1, wherein the particle formation process includes undercooling of the fluid or molten solder material (54) and creating the liquid cores

(52) and forming the solid shells (53) by oxidation and/or by layer deposition.

3. The method according to any of claims 1 and 2, wherein the centres of particle formation are nuclei (100) provided on a side of the solder material (54) facing the interlayer structure (60) or on a side of the solder material (54) facing away from the interlayer structure (60) .

4. The method according to any of claims 1 to 3, wherein the interlayer structure (60) comprises holes (61) , which form the centres of particle formation.

5. The method according to any of the preceding claims, wherein the interlayer structure (60) is an anti-wetting layer .

6. The method according to any of the preceding claims, wherein the interlayer structure (60) is an organic or inorganic layer.

7. A method for producing a connection means (4) of a component (1) of an electronic device (10) , the method comprising :

- providing a component base structure (20) for producing at least one component base body (2) , wherein the component base structure (20) has a main surface (20A) ,

- providing a particle structure (50) on the main surface (20A) , wherein particles (51) of the particle structure (50) comprise in each case a liquid core (52) and a solid shell (53) surrounding the liquid core (52) , and the liquid core (52) comprises a solder material (54) , and

- providing an interlayer structure (60) between the main surface (20A) and the particle structure (50) , wherein the interlayer structure (60) is applied on the main surface (20A) after the particle structure (50) is provided. 8. The method according to claim 7, wherein providing the particle structure (50) includes applying the particles (51) on the main surface (20A) , and providing the interlayer structure (60) includes conformally depositing the interlayer structure (60) on the particles (51) .

9. The method according to any of claims 7 and 8, wherein the interlayer structure (60) is an oxide or metal layer.

10. The method according to any of claims 7 to 9, wherein the interlayer structure (60) is removed in interspaces (55) between the particles (51) .

11. The method according to any of claims 7 to 10, wherein a wettable layer structure (70) is arranged on the main surface

(20A) between the component base structure (20) and the interlayer structure (60) .

12. A component (1) of an electronic device (10) , comprising

- a component base body (2) and

- a connection means (4) , wherein the connection means (4) includes :

- a particle layer (5) , wherein particles (51) of the particle layer (5) comprise in each case a liquid core (52) and a solid shell (53) surrounding the liquid core (52) , and the liquid core (52) comprises a solder material (54) , and

- an interlayer (6) between the component base body (2) and the particle layer (5) , wherein the connection means (4) is arranged on an outer surface (2A) of the component base body (2) and is provided to form a connection layer (11) by releasing the solder material (54) from the solid shells (53) of the particles (51) at a soldering temperature lower than a melting point of the solder material (54) .

13. The component (1) according to claim 12, wherein the solder material (54) comprises at least one of the following materials: Sn, Bi, Ag, SnAgCu, SnAg, SnBi, AuSn.

14. The component (1) according to any of claims 12 and 13, wherein the solid shell (53) comprises an inorganic material including an oxide and/or a nitride.

15. The component (1) according to any of claims 12 to 14, wherein the interlayer (6) contains an inorganic material including an oxide and/or a nitride and/or a metal.

16. The component (1) according to any of claims 12 to 15, wherein the interlayer (6) contains an organic material including a plastic material.