Method for Producing an Electronic Device and Electronic Device

Abstract

A method for producing an electronic device and an electronic device are disclosed. In an embodiment a method for producing an electronic device includes attaching semiconductor chips on a carrier, applying a fluoropolymer to main surfaces of the semiconductor chips facing away from the carrier and a main surface of the carrier facing the semiconductor chip thereby forming an encapsulation layer including a fluoropolymer, structuring the encapsulation layer thereby forming cavities in the encapsulation layer and applying a metal layer in the cavities.

Claims

1-15. (canceled)

16. A method for producing an electronic device, the method comprising: applying and attaching semiconductor chips on a carrier; applying a fluoropolymer to main surfaces of the semiconductor chips facing away from the carrier and a main surface of the carrier facing the semiconductor chip thereby forming an encapsulation layer comprising a fluoropolymer; structuring the encapsulation layer thereby forming cavities in the encapsulation layer; and applying a metal layer in the cavities.

17. The method according to claim 16, wherein the method produces a radiation-emitting optoelectronic device, and wherein a semiconductor chip is adapted to emit UV radiation during operation.

18. The method according to claim 16, wherein the fluoropolymer comprises a first structural unit A of the following general formula: ##STR00031## wherein the substituents X1 to X4 are each independently selected from the group consisting of hydrogen, halogens, R and OR, wherein R is in each case a hydrocarbon residue C1-C10 or a fluorinated hydrocarbon residue C1-C10, and wherein at least one of the substituents X1 to X4 is fluorine.

19. The method according to claim 18, wherein the fluoropolymer is a copolymer comprising, in addition to the first structural unit A, at least one further structural unit B, different from the structural unit A, of the following general formula: ##STR00032## wherein the substituents Y1 to Y4 are each independently selected from the group consisting of hydrogen, halogens, R and OR, and wherein each R is a hydrocarbon residue C1-C10 or a fluorinated hydrocarbon residue C1-C10.

20. The method according to claim 18, wherein the fluoropolymer is a copolymer comprising, in addition to the first structural unit A, at least one further structural unit B, different from the structural unit A, of the following general formula: ##STR00033##

21. The method according to claim 16, wherein the fluoropolymer is a copolymer having a first structural unit A and a second structural unit B, wherein the structural unit A is selected from the group consisting of: ##STR00034## wherein the structural unit B is selected from the group consisting of: ##STR00035## and wherein each R is a hydrocarbon residue C1-C10 or a fluorinated hydrocarbon residue C1-C10.

22. The method according to claim 16, wherein the fluoropolymer is a polymer selected from the following group consisting of Ethylene chlorotrifluoroethylene copolymer (ECTFE), Ethylene tetrafluoroethylene copolymer (ETFE), Perfluoroalkoxy polymers (PFA), Fluorinated ethylene-propylene copolymer (FEP), Polyvinyl fluoride (PVF), Polychlorotrifluoroethylene (PCTFE), Copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV), Copolymer of tetrafluoroethylene and 2,2 bis(trifluoromethyl)-4,5-difluoro-1,3-dioxolane (PTFE-AF), Polytetrafluoroethylene (PTFE), and Polyvinylidene fluoride (PVDF).

23. The method according to claim 16, wherein applying the fluoropolymer comprises applying a film including the fluoropolymer by hot stamping or lamination.

24. The method according to claim 16, wherein applying the fluoropolymer comprises applying the fluoropolymer by injection molding, injection compression molding, transfer molding, hot stamping or welding.

25. The method according to claim 16, wherein structuring the encapsulation layer comprises structuring the encapsulation layer by hot stamping or by sawing.

26. The method according to claim 16, further comprising roughening the carrier.

27. The method according to claim 26, wherein roughening the carrier comprise roughening the carrier by powder coating, etching or a plasma treatment.

28. The method according to claim 27, roughening the carrier comprises forming anchorages on the main surface of the carrier.

29. The method according to claim 28, wherein the anchorages protrude 10 to 100 m above the main surface of the carrier.

30. The method according to claim 16, wherein applying the metal layer comprises applying the metal layer by sputtering.

31. A radiation-emitting optoelectronic device comprising: a semiconductor chip arranged on a carrier, the semiconductor chip configured to emit UV radiation during operation; an encapsulation layer comprising a fluoropolymer arranged above a main surface of the semiconductor chip facing away from the carrier and above a main surface of the carrier facing the semiconductor chip; and a metal layer disposed above side surfaces of the semiconductor chip and above and in direct contact with the encapsulation layer.

32. The Radiation-emitting optoelectronic device according to claim 31, wherein the fluoropolymer comprises: a first structural unit A of the following general formula: ##STR00036## and a second structural unit B of the following general formula: ##STR00037## wherein R is CF2CF2CF3, and wherein a proportion of the structural unit B in the copolymer is 1.5-2 mol %; a combination of MFA and PFA of the compositions just mentioned; FEP-1 with a first structural unit A ##STR00038## and with a second structural unit B ##STR00039## wherein R is CF3 and wherein the proportion of the structural unit B in the copolymer is 7-7.5 mol %.

33. A method for producing an electronic device the method comprising: applying and attaching semiconductor chips on a carrier; applying a fluoropolymer to main surfaces of the semiconductor chips facing away from the carrier and a main surface of the carrier facing the semiconductor chip thereby forming an encapsulation layer comprising the fluoropolymer; structuring the encapsulation layer comprising the fluoropolymer thereby forming cavities in the encapsulation layer, wherein the cavities are laterally delimited by the encapsulation layer and delimited from below by the carrier; and applying a metal layer in the cavities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0130] Further advantageous embodiments and developments of the invention will become apparent from the embodiments described below in connection with the figures.

[0131] Showing it:

[0132] FIGS. 1 to 10 show a method for producing a radiation-emitting optoelectronic device;

[0133] FIG. 11 shows various fluoropolymers and their melting points;

[0134] FIG. 12 shows melting temperatures for different fluoropolymers; and

[0135] FIG. 13 shows a transmission of different fluoropolymers.

[0136] In the exemplary embodiments and figures, identical, identical or identically acting elements can each be provided with the same reference numerals. The illustrated elements and their proportions with each other are not to be regarded as true to scale, but individual elements, such as layers, components, components and areas, may be oversized for better representability and/or better understanding.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0137] FIG. 1 shows a semiconductor chip 2 comprising an active epitaxial layer sequence with an n-conducting layer 2n and a p-conducting layer 2p, which is suitable for emitting a primary radiation in the UV range of the electromagnetic spectrum during operation of the radiation-emitting optoelectronic device. The semiconductor chip 2 is arranged or grown on a substrate 1, in particular a sapphire substrate. The semiconductor chip 2 is based, for example, on aluminum indium gallium nitride. The semiconductor chip 2 is attached to a first connection 4 and a second connection 5 and is electrically contacted to these connections. In this case, the connection 4 contacts the n-conducting layer 2n and the connection 5 contacts the p-conducting layer 2p. The connection 4 and 5 are formed from a metal which has a reflectivity for UV radiation greater than 60%, preferably greater than 70%, particularly preferably greater than 80%, for example, silver or aluminum. As a result, the primary radiation emitted by the semiconductor chip can be reflected back into the semiconductor chip and emitted from the semiconductor chip via the main surface 2a. Between the p-conducting layer 2p and the connection 4 and 5, an insulating layer I is arranged. In particular, the insulating layer I isolates the first connection 4 from the p-conducting layer 2p. Between the p-conducting layer 2p and the insulating layer I, in particular, a mirror layer may be arranged above the second connection 5 (not shown here). Alternatively, the second connection 5 may have a direct contact with the p-conducting layer 2p, so it cannot be separated from it by an insulating layer. In this embodiment, the insulating layer I is located only between the first connection 4 and the p-conducting layer 2p.

[0138] Furthermore, FIG. 1 shows a schematic side view of a carrier 3. The carrier has through-connections 4a and 5a. On a main surface of the carrier 3a are anchorages 6, which are created by a roughening. The main surface of the carrier 3a is only partially roughened. In particular, the roughening takes place at locations of the main surface of the carrier 3a, on which no semiconductor chips 2 are applied in the following method step, that is to say in the interspaces 8a between the individual semiconductor chips 2. For example, the carrier 3 consists of silicon and can have pyramid-shaped anchorages 6. The pyramid-shaped anchorages 6 can be made by etching the silicon and utilizing its crystal orientation.

[0139] In FIG. 2, the semiconductor chips 2 are applied and fixed on the carrier 3. In each case, the connection 4 is applied to the through-connection 4a and the connection 5 to the through-connection 5a. The attachment of the semiconductor chips 2 on the main surface of the carrier 3a can be attached by gluing or soldering. The semiconductor chips 2 are arranged at a distance from one another on the carrier 3, so that an interspace 8a is formed between the individual semiconductor chips 2.

[0140] FIG. 3 shows that the substrate 1, in particular the sapphire substrate on which the epitaxial layer sequence has grown, is removed. However, it is also possible that the sapphire substrate remains partially or completely above the semiconductor chip 2. If the sapphire substrate remains partially or completely above the semiconductor chip 2, it can have topography differences at its surface, for example, about 150 m. As a result, the subsequently applied encapsulation layer 7 can adhere very well to the surface of the sapphire substrate.

[0141] For better light extraction, the semiconductor chip 2, in particular the main surface of the semiconductor chip 2a facing away from the carrier can be roughened in order to improve the coupling out of the light to the environment, after a passivation of the semiconductor chip 2 can take place, for example, by the application of SiO.sub.2 (not shown).

[0142] According to FIG. 4, an encapsulation layer 7 is applied over or onto the semiconductor chips 2. In particular, the encapsulation layer 7 is applied to the main surface of the carrier 3a facing the semiconductor chips, the side surfaces of the semiconductor chips 2c and to the main surfaces of the semiconductor chips 2a facing away from the carrier 3. In this case, the encapsulation layer 7 can be laminated, for example, as a film. The film comprises a fluoropolymer, for example, fluorinated ethylene-propylene copolymer (FEP). By the method according to embodiments of the invention fluoropolymers can be used in radiation-emitting optoelectronic devices, which are usually very difficult to process due to their hardness and brittleness. By the anchorages 6, the adhesion of the film on the carrier 3 is improved.

[0143] According to FIG. 5, a photoresist 9 is applied over the entire surface of the encapsulation layer 7 on the main surface of the encapsulation layer 7a facing away from the carrier 3.

[0144] In FIG. 6, the encapsulation layer 7 and the photoresist 9 comprising the fluoropolymer are structured. In particular, this structuring takes place by sawing in each case between two semiconductor chips 2 in the interspaces 8a. The sawing can for example be done with a saw blade width of 100 to 200 m. Cavities 8 are formed between the individual semiconductor chips 2. The cavities 8 are delimited laterally by the encapsulation layer 7 and the photoresist 9 and from below by the carrier 3. In particular, the side surfaces of the cavity 8c are aligned perpendicular or nearly perpendicular to the extension plane of the carrier 3.

[0145] In FIG. 7, a metal layer 10 is applied in the cavity 8 and above the photoresist 9, in particular, the deposition of the metal, for example, aluminum, takes place by sputtering. In particular, the metal layer 10 is deposited on the side surfaces of the cavity 8c above the encapsulation layer 7 and the photoresist 9 and on the main surface of the photoresist 9 facing away from the carrier 3. The part of the main surface of the carrier enclosed by the cavity 8 is not completely coated with the metal layer 10. There still remains a cavity 12 between the individual semiconductor chips 2.

[0146] In FIG. 8, the photoresist 9 is removed. This is done for example by a lift-off method. The lift-off process dissolves the photoresist 9 under the metal layer 10 and lifts the metal layer 10 over the photoresist 9 under high pressure.

[0147] Subsequently, a separation takes place to form the radiation-emitting optoelectronic devices, which is shown in FIG. 9. The separation takes place, for example, by sawing the carrier 3 in the cavity 12.

[0148] In the method step of FIG. 10, a lens ii may be applied over the encapsulation layer 7, for example, by molding. The radiation-emitting device produced in this way is a so-called top emitter, which means that the radiation is emitted upwards to the environment via the encapsulation layer 7.

[0149] FIG. 11 shows a table with the preferred fluoropolymers of the encapsulation layer. In the first column, the respective abbreviation of the fluoropolymer, in the second column, the structural unit A, in the third column, the structural unit B, if a copolymer is involved, in the fourth column the proportion of the structural unit B in mol % and in column B indicated the melting temperature of the respective polymer. The fluoropolymers MFA, PFA-1 and FEP-1 have proven to be particularly stable to the effect of temperature and UV radiation.

[0150] FIG. 12 shows melting temperatures for different fluoropolymers. At melting temperatures below 320 C., the fluoropolymers can be applied by injection molding, injection compression molding or transfer molding. If the melting temperatures are higher, the fluoropolymers can be processed into a film that can be laminated or applied and fastened by hot stamping or welding. At melting temperatures above 320 C., the fluoropolymers can be subjected to a sintering process. For this purpose, individual powder particles are sintered together to form a homogeneous structure. At temperatures above 350 C. the crystallization melting point is exceeded and the PTFE enters the amorphous state, here as mod. PTFE . At a melting temperature of 305 C., the PFA can be melted. At a temperature of 320 C., the so-called Moldflon can be melted. At a temperature of 327 C., the mod. PTFE, the polytetrafluoroethylene, are melted. At 327 C., the PTFE can be melted. The PTFE is not moldable by nature. For example, it can only be injection-molded by side chain modification, for example, Moldflon. The Moldflon is a fluoropolymer available from Elring Klinger Kunststofftechnik.

[0151] FIG. 13 shows the relative transmission Tr in percent of different fluoropolymers at different wavelengths in nm. The data are based on measurements of an encapsulation layer consisting of the respective fluoropolymer with a layer thickness of 0.5 mm in each case. The curve provided with the reference numeral I shows the transmission of Hyflon PFA, the curve provided with the reference numeral II shows the transmission of Hyflon PFA M640, the curve provided with the reference numeral III shows the transmission of Hyflon MFA F1540 and with the reference numeral IV curve shows the transmission of a fluoropolymer consisting of a combination of PFA-1 and MFA.

[0152] The embodiments described in connection with the figures and their features can also be combined with each other according to further embodiments, even if such combinations are not explicitly shown in the figures. Furthermore, the embodiments described in connection with the figures may have additional or alternative features according to the description in the general part.

[0153] The invention is not limited by the description based on the embodiments of these, but the invention includes any novel feature as well as any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.