Method for producing an optoelectronic component and wafer

Abstract

A method for producing an optoelectronic component comprises providing a wafer (100) with a plurality of epi structures (210) arranged on a top side of the wafer (100), wherein the epi structures (210) are separated by clearances (220), providing a sheet (300) of wavelength converting material, arranging the sheet (300) above the epi structures (210), forming a mask (400) on top of the sheet (300), wherein the mask (400) comprises openings (420) arranged above the clearances (220), removing parts of the sheet (300) arranged above the clearances (220), and removing the mask (400).

Description

[0001] METHOD FOR PRODUCING AN OPTOELECTRONIC COMPONENT AND WAFER

[0002] DESCRIPTION

[0003] The present invention relates to a method for producing an optoelectronic component and to a wafer having a plurality of epi structures and parts of a sheet of wavelength converting material arranged on a top side of the wafer .

[0004] This patent application claims the priority of German patent application 10 2023 120 425 . 4 , the disclosure content of which is hereby incorporated by reference .

[0005] It is known in the state of the art to provide optoelectronic components with wavelength converting elements .

[0006] It is an obj ect of the present invention to provide a method for producing an optoelectronic component . It is a further obj ect of the present invention to provide a wafer having a plurality of epi structures and parts of a sheet of wavelength converting material arranged on a top side o f the wafer . These obj ectives are achieved by a method and a wafer according to the independent claims . Preferred embodiments are disclosed in the dependent claims .

[0007] A method for producing an optoelectronic component comprises providing a wafer with a plurality of epi structures arranged on a top side of the wafer, wherein the epi structures are separated by clearances , providing a sheet of wavelength converting material , arranging the sheet above the epi structures , forming a mask on top of the sheet , wherein the mask comprises openings arranged above the clearances , removing parts of the sheet arranged above the clearances , and removing the mask .

[0008] This method allows to arrange individual segments o f a sheet of wavelength converting material on upper sides of a plurality of individual epi structures in a common proces s . The sections of the sheet arranged on the epi structures can have a well-defined thickness . This may result in predictable conversion characteristics , allowing for a high colour yield .

[0009] In an embodiment of the method, providing the wafer comprises providing the wafer having a blank top side , epitaxially growing an epi layer on the top side , and structuring the epi layer to form the plurality of epi structures . In this variant , the epi structures do not need to be trans ferred to another wafer before arranging the sheet of wavelength converting material on the epi structures .

[0010] In another embodiment of the method, providing the wafer comprises providing the wafer having a blank top side , providing a further wafer with a plurality of epi structures arranged on a top side of the further wafer, and trans ferring the epi structures from the further wafer to the top side o f the wafer . In this variant , the epi structures may be trans ferred and optionally flipped before arranging the sheet o f wavelength converting material on the epi structures .

[0011] In an embodiment of the method, providing the sheet comprises producing the sheet by tape casting . Advantageously, tape casting allows to produce the sheet with a predictable thickness and a high homogeneity .

[0012] In an embodiment of the method, the sheet comprises a matrix material and wavelength converting particles embedded into the matrix material . The matrix material may be a polysiloxane , for example .

[0013] In an embodiment of the method, the mask is formed from a photoresist . Advantageously, this allows for a simple forming of the mask .

[0014] In another embodiment , the mask is formed as a hardmask . Advantageously, this allows for a high flexibility in choosing a process to remove those parts of the sheet that are arranged above the clearances .

[0015] In an embodiment of the method, the parts of the sheet that are arranged above the clearances are removed by etching . In particular, the parts of the sheet that are arranged above the clearances may be removed by plasma etching . Advantageously, this allows to reliably remove parts of the sheet of wavelength converting material without damaging other parts of the arrangement .

[0016] In an embodiment of the method, the epi structures comprise contact pads . The mask comprises openings arranged above the contact pads . Those parts of the sheet that are arranged above the contact pads are removed . Advantageously, this allows to adj ust the shape of the sections of the sheet of wavelength converting material arranged on the epi structures such that the contact pads are not covered by the wavelength converting material and remain accessible .

[0017] A wafer has a plurality of epi structures arranged on a top side of the wafer . The epi structures are separated by clearances . Parts of a sheet of a wavelength converting material are arranged on the epi structures but not above the clearances .

[0018] Advantageously, the parts of the sheet of wavelength converting material arranged on the epi structures may have a well- defined thickness , resulting in predictable convers ion properties .

[0019] Another variant of a method for producing an optoelectronic component comprises providing a wafer with a plural ity of epi structures arranged on a top side of the wafer, wherein the epi structures are separated by clearances , arranging a layer of wavelength converting material on the top side o f the wafer, wherein the layer covers the epi structures , forming a mask on top of the layer, wherein the mask comprises openings arranged above the clearances , removing parts of the layer arranged above the clearances , and removing the mas k . The layer of wavelength converting material may be appl ied by spray coating or by doctor blading, for example .

[0020] This variant of the method allows to arrange individual segments of a layer of wavelength converting material on upper sides of a plurality of individual epi structures in a common process . The sections of the layer arranged on the epi structures can have a well-defined thickness . This may result in predictable conversion characteristics , allowing for a high colour yield .

[0021] The above-described properties , features and advantages of the invention, as well as the way in which they are achieved, will become more clearly and comprehensively understandable in connection with the following description of exemplary embodiments , which will be explained in more detail in connection with the drawings in which, in schematic representation :

[0022] Fig . 1 shows a sectional view of a wafer with a plurality of epi structures arranged on a top side of the wafer ;

[0023] Fig . 2 shows a sheet of wavelength converting material arranged above the epi structures ;

[0024] Fig . 3 shows a layer of photoresist arranged on the sheet of wavelength converting material ;

[0025] Fig . 4 shows a mask formed from the layer of photoresist on top of the sheet of wavelength converting material ;

[0026] Fig . 5 shows the sheet of wavelength converting material after removing parts of the sheet arranged above clearances between the epi structures ;

[0027] Fig . 6 shows the epi structures with sections of the sheet arranged on top of the epi structures ; Fig . 7 shows a top view of the epi structures and segments of the sheet of wavelength converting material according to another embodiment ; and

[0028] Fig . 8 shows a layer of wavelength converting material arranged above the epi structures .

[0029] Fig . 1 shows in a schematic sectional view a wafer 100 having a flat top side 101 . The wafer 100 may comprise a semiconductor material , a glass material or another material .

[0030] A structured epi layer 200 is arranged on the top s ide 101 of the wafer 100 . The epi layer 200 is structured such that a plurality of separate epi structures 210 is formed . The epi structures 210 are arranged on the top side 101 of the wafer at a distance from each other . The epi structures 210 may be arranged in a regular matrix pattern, for example . The epi structures 210 are separated by clearances 220 . Each epi structure 210 comprises an upper side 201 facing away from the top side 101 of the wafer 100 and a lower side 202 facing towards the top side 101 of the wafer 100 .

[0031] Throughout this description, the terms "epi layer" and "epi structure" refer to layers and structures produced by epitaxial growth . The epi layer 200 has been grown by epitaxy and comprises semiconductor materials . The epi structures 210 may form LEDs , for example .

[0032] The epi layer 200 may have been grown directly on the wafer 100 . In this case , the epi layer 200 has been epitaxially grown on the top side 101 of the wafer 100 . Afterwards , the epi layer 200 has been structured to form the plurality of epi structures 210 .

[0033] Alternatively, the epi structures 210 may have been transferred from a further wafer to the formerly blank top side 101 of the wafer 100 . In this case , the epi layer 200 may have been grown and structured on a top side of the further wafer to form the plurality of epi structures 210 . Afterwards , the epi structures 210 of the epi layer 200 have been trans ferred to the top side 101 of the wafer 100 us ing one of the established trans fer methods that are known to a person of skill in the art .

[0034] Fig . 2 shows a schematic sectional view of a proces sing state that follows the depiction of Fig . 1 . A sheet 300 o f wavelength converting material 330 has been provided and arranged above the upper sides 201 of the epi structures 210 .

[0035] The wavelength converting material 330 is designed to convert light into light of a di f ferent wavelength . In particular, the wavelength converting material 330 is designed to convert at least parts of light emitted by the epi structures 210 into light having a di f ferent wavelength .

[0036] The wavelength converting material 330 may comprise a matrix material 331 and wavelength converting particles 332 embedded into the matrix material 331 . The matrix material 331 may be a polysiloxane , for example .

[0037] Before arranging the sheet 300 above the epi structures 210 , the sheet 300 may have been produced separately . The sheet 300 may have been produced by tape casting, for example . It is desirable that the sheet 300 comprises a well-de fined thickness and a homogeneous composition .

[0038] Arranging the sheet 300 above the epi structures 210 may have been carried out by laminating the sheet 300 onto the upper sides 201 of the epi structures 210 such that a lower side 302 of the sheet 300 is oriented towards the upper sides 201 of the epi structures 210 . An upper side 301 of the sheet 300 faces away from the top side 101 of the wafer 100 .

[0039] The clearances 220 separating the epi structures 210 on the top side 101 of the wafer 100 remain as voids between the top side 101 of the wafer 100 and the lower side 302 of the sheet 300 .

[0040] Fig . 3 shows a schematic depiction of a processing state that follows the depiction of Fig . 2 . A layer of photoresist 430 has been arranged on the upper side 301 of the sheet 300 . The photoresist 430 may have been applied by spin coating, for example .

[0041] Fig . 4 shows a processing state that follows the depiction of Fig . 3 . The photoresist 430 has been structured such that a mask 400 is formed on the upper side 301 of the sheet 300 . Structuring of the photoresist 430 may have been carried out using standard methods such as exposing parts of the photoresist 430 and developing the photoresist 430 . The mask 400 comprises openings 420 arranged above the clearances 220 and impenetrable sections 410 arranged above the epi structures 210 .

[0042] In an alternative variant , the mask 400 is formed as a hard- mask . The hardmask can be formed using established standard technologies involving, for example , photolithography .

[0043] First parts 310 of the sheet 300 of wavelength converting material 330 are covered by the impenetrable sections 410 of the mask 400 . Second parts 320 of the sheet 300 are exposed through the openings 420 of the mask 400 . The first parts 310 of the sheet 300 are arranged on the epi structures 210 . The second parts 330 of the sheet 300 are arranged above the clearances 220 .

[0044] Fig . 5 shows a processing state that follows the depiction of Fig . 4 . The second parts 320 of the sheet 300 that were previously arranged above the clearances 220 have been removed . The first parts 310 of the sheet 300 that are arranged on the epi structures 210 have not been removed . Removing the second parts 320 of the sheet 300 may have been achieved by etching, for example . In particular, the second parts 320 of the sheet 300 may have been removed by plasma etching, for example .

[0045] The plasma process may be chosen in dependence on the wavelength converting material 330 of the sheet 300 , in particular in dependence on the matrix material 331 . Plasma etching may remove the matrix material 331 in the second parts 320 of the sheet 300 . Once the matrix material 331 is etched, the formerly embedded wavelength converting particles 332 are not bound to the remaining sheet 300 anymore and can easily be removed, e . g . , by a gas or liquid flow-based cleaning .

[0046] Fig . 6 shows a processing state that follows the depiction of Fig . 5 . The mask 400 has been removed .

[0047] The wafer 100 remains with the plurality of epi structures 210 arranged on the top side 101 of the wafer 100 . The epi structures 210 are separated by the clearances 220 . The first parts 310 of the sheet 300 of wavelength converting material 330 are arranged on the upper sides 201 of the epi structures 210 . No parts of the sheet 300 of wavelength converting material 330 are arranged above the clearances 220 .

[0048] Each epi structure 210 and the respective first part 310 of the sheet 300 of wavelength converting material 330 arranged on the upper side 201 of the epi structure 210 forms an optoelectronic component 10 . Processing of the optoelectronic components 10 may continue after the processing state depicted in Fig . 6 . For example , a processing step to separate the individual optoelectronic components 10 may follow .

[0049] Fig . 7 shows a schematic top view of an alternative variant of the wafer 100 in the processing state depicted in Fig . 6 . In this variant , the epi structures 210 comprise contact pads 215 on their upper sides 201 . The contact pads 215 are provided to electrically connecting the epi structure 210 by means of a bond process , for example . In the example depicted in Fig . 7 , the contact pad 215 is arranged in a corner of the upper side 201 of the epi structure 210 in each case . The contact pads 215 may be arranged at di f ferent positions , however .

[0050] In Fig . 7 , the first parts 310 of the sheet 300 of wavelength converting material 330 are shaped such that the contact pads 215 are not covered by the first parts 310 of the sheet 300 but are exposed and accessible .

[0051] To this end, in this case , the mask 400 depicted in Fig . 4 has been formed such that the openings 420 of the mask 400 include the area above the contact pads 215 . This means that the openings 420 of the mask 400 have also been arranged above the contact pads 215 . In the following proces sing step, removing the second parts 320 of the sheet 300 has in this case included removing the parts of the sheet 300 that were arranged above the contact pads 215 of the epi structures 210 .

[0052] Fig . 8 shows a schematic sectional view of a proces sing state that follows the depiction of Fig 1 in an alternative variant of the method for producing the optoelectronic components 10 . A layer 500 of wavelength converting material 330 has been arranged on the top side 101 of the wafer 100 . The layer 500 covers the epi structures 210 and also fills the clearances 220 between the epi structures 210 . An upper side 501 of the layer 500 faces away from the top side 101 of the wafer 100 . A lower side 502 of the layer 500 is oriented towards the upper sides 201 of the epi structures 210 and towards the top side 101 of the wafer 100 .

[0053] The wavelength converting material 330 comprises the same properties as described above with respect to the sheet 300 of wavelength converting material 330 . The layer 500 of wavelength converting material 330 may have been applied by spray coating or by doctor blading, for example . In this variant of the method for producing the optoelectronic components 10 , the layer of photoresist 430 is arranged on the upper side 501 of the sheet 500 in a processing step that follows the depiction of Fig . 8 . Then, the method continues as described above with respect to Figs . 3 to 7 .

[0054] The invention has been illustrated and described in more detail with the aid of the preferred exemplary embodiments . The invention is not , however, restricted to the examples disclosed . Rather, other variants may be derived there from by the person skilled in the art .

[0055] REFERENCE SYMBOLS optoelectronic component wafer top side epi layer upper side lower side epi structure contact pad clearance sheet upper side lower side first part second part wavelength converting material matrix material wavelength converting particles mask impenetrable section opening photoresist layer upper side lower side

Claims

CLAIMS1. A method for producing an optoelectronic component (10) comprising- providing a wafer (100) with a plurality of epi structures (210) arranged on a top side (101) of the wafer(100) , wherein the epi structures (210) are separated by clearances (220) ;- providing a sheet (300) of wavelength converting material (330) ;- arranging the sheet (300) above the epi structures (210) ;- forming a mask (400) on top of the sheet (300) , wherein the mask (400) comprises openings (420) arranged above the clearances (220) ;- removing parts (320) of the sheet (300) arranged above the clearances (220) ;- removing the mask (400) .

2. The method according to claim 1, wherein providing the wafer (100) comprises- providing the wafer (100) having a blank top side(101) ;- epitaxially growing an epi layer (200) on the top side (101) ;- structuring the epi layer (200) to form the plurality of epi structures (210) .

3. The method according to claim 1, wherein providing the wafer (100) comprises- providing the wafer (100) having a blank top side (101) ;- providing a further wafer with a plurality of epi structures (210) arranged on a top side of the further wafer;- transferring the epi structures (210) from the further wafer to the top side (101) of the wafer (100) .

4. The method according to one of the previous claims, wherein providing the sheet (300) comprises- producing the sheet (300) by tape casting.

5. The method according to one of the previous claims, wherein the sheet (300) comprises a matrix material (331) and wavelength converting particles (332) embedded into the matrix material (331) .

6. The method according to one of the previous claims, wherein the sheet (300) is arranged above the epi structures (210) by laminating the sheet (300) onto the epi structures (210) .

7. The method according to one of the previous claims, wherein the mask (400) is formed from a photoresist (430) .

8. The method according to one of claims 1 to 6, wherein the mask (400) is formed as a hardmask.

9. The method according to one of the previous claims, wherein the parts (320) of the sheet (300) that are arranged above the clearances (220) are removed by etching.

10. The method according to claim 9, wherein the parts (320) of the sheet (300) that are arranged above the clearances (220) are removed by plasma etching .

11. The method according to one of the previous claims, wherein the epi structures (210) comprise contact pads (215) , wherein the mask (400) comprises openings (420) arranged above the contact pads (215) , wherein parts of the sheet (300) arranged above the contact pads (215) are removed.12.A wafer (100) having a plurality of epi structures (210) arranged on a top side (101) of the wafer (100) , wherein the epi structures (210) are separated by clearances (220) , wherein parts (310) of a sheet (300) of wavelength converting material (330) are arranged on the epi structures (210) but not above the clearances (220) .

13. A method for producing an optoelectronic component (10) comprising- providing a wafer (100) with a plurality of epi structures (210) arranged on a top side (101) of the wafer (100) , wherein the epi structures (210) are separated by clearances (220) ;- arranging a layer (500) of wavelength converting material (330) on the top side (101) of the wafer (100) , wherein the layer (500) covers the epi structures (210) ;- forming a mask (400) on top of the layer (500) , wherein the mask (400) comprises openings (420) arranged above the clearances (220) ;- removing parts (320) of the layer (500) arranged above the clearances (220) ;- removing the mask (400) .

14. The method according to claim 13, wherein the layer (500) of wavelength converting material (330) is arranged by spray coating.

15. The method according to claim 13, wherein the layer (500) of wavelength converting material (330) is arranged by doctor blading.

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