Method for producing an optic device, optic device and assembly comprising such an optic device

Abstract

A method for producing an optic device, an optic device and an assembly including such an optic device are disclosed. In an embodiment, the method includes providing an active medium mechanically carried by a carrier body or included in the carrier body; applying an adhesive layer to at least one of the active medium or the carrier body, wherein the adhesive layer comprises at least one organic material and is applied by physical or chemical vapor phase deposition, and wherein a thickness of the adhesive layer is between 20 nm and 0.6 m inclusive.

Claims

1. A method for producing an assembly, the method comprising: providing an optic device which is an LED chip comprising an active medium; providing a support being a metallic lead frame; applying an adhesive layer to at least one of the optic device or the support; and mounting the optic device on the support so that the optic device and the support are permanently and firmly connected, wherein the adhesive layer comprises at least one organic material and is applied by physical or chemical vapor phase deposition, and wherein a thickness of the adhesive layer is between 20 nm and 0.6 m inclusive.

2. The method according to claim 1, wherein the active medium is a semiconductor layer sequence comprising an active zone configured to produce electromagnetic radiation by electroluminescence during operation, and wherein the LED chip comprises a carrier body which is a substrate to which the semiconductor layer sequence is applied or on which the semiconductor layer sequence is grown.

3. The method according to claim 2, wherein the adhesive layer is solely applied on a side of the substrate facing away from the semiconductor layer sequence, and wherein the substrate and the adhesive layer are light-transmissive for the electromagnetic radiation.

4. The method according to claim 1, wherein the adhesive layer comprises at least one of a polyimide, a siloxane, an acrylate or an epoxide.

5. The method according to claim 1, wherein the adhesive layer comprises a silicone-epoxide hybrid material.

6. The method according to claim 1, wherein the adhesive layer is applied by at least one of pulsed laser deposition, sputtering, initiated chemical vapor phase deposition or oxidative chemical vapor phase deposition.

7. The method according to claim 1, wherein the adhesive layer essentially consists of a plurality of organic materials and is grown of a plurality of sub-layers which are stacked one above the other.

8. The method according to claim 7, wherein the adhesive layer comprises a non-adhesive cover layer which is an outmost layer, and wherein mounting the optic device to the support comprises destroying the cover layer during mounting of the optic device.

9. The method according to claim 1, wherein the support has a mounting face with a roughening, wherein, during mounting, the adhesive layer is pressed onto the mounting face, and wherein the roughening penetrates the adhesive layer so that the support comes in direct contact with at least one of a carrier body of the LED hip or the active medium in places.

10. The method according to claim 1, wherein at least one of the support, a carrier body of the LED chip or the active medium comprises electric contact areas, wherein, during mounting on the support, the adhesive layer remains as a contiguous layer without holes so that the adhesive layer completely covers the electric contact areas, and wherein the adhesive layer is electrically conductive.

11. The method according to claim 1, wherein at least one of the support, a carrier body of the LED chip and r active medium comprises electric contact areas, wherein, during mounting on the support, the electric contact areas remain free of the adhesive layer, and wherein the adhesive layer is electrically insulating.

12. The method according to claim 1, wherein, during mounting on the support, the adhesive layer is cured by a temperature increase.

13. The method according to claim 1, wherein, during mounting on the support, the adhesive layer is cured by radiation that initiates a photochemical reaction, and wherein, immediately before mounting, the adhesive layer has a viscosity of at most 100 Pa.Math.s at a temperature of 300 K.

14. The method according to claim 13, wherein the radiation to cure the adhesive layer is generated by a LED chip.

15. A method for producing an assembly comprising: providing an optic device comprising an active medium mechanically carried by a carrier body or included in the carrier body; applying an adhesive layer to at least one of the active medium or the carrier body; and mounting the optic device that includes the adhesive layer on a support so that the optic device and the support are permanently and firmly connected, wherein the adhesive layer comprises at least one organic material and is applied by physical or chemical vapor phase deposition, wherein the support has a mounting face with a roughening, wherein, during mounting, the adhesive layer is pressed onto the mounting face, wherein the roughening penetrates the adhesive layer so that the support comes in direct contact with at least one of the carrier body or the active medium in places, and wherein a thickness of the adhesive layer is between 20 nm and 0.6 m inclusive.

16. The method according to claim 15, wherein the active medium is a phosphor configured to produce electromagnetic radiation by photoluminescence during operation, wherein the carrier body, and wherein the carrier body and the adhesive layer are light-transmissive for the electromagnetic radiation.

17. The method according to claim 16, wherein the carrier body is a matrix material in which the phosphor is embedded, and wherein the phosphor is in places in direct contact with the adhesive layer.

18. A method for producing an assembly comprising: providing an optic device comprising an active medium mechanically carried by a carrier body or included in the carrier body; providing a support being a metallic lead frame; applying an adhesive layer to at least one of the optic device or the support; and mounting the optic device on the support so that the optic device and the support are permanently and firmly connected, wherein the adhesive layer comprises at least one organic material and is applied by physical or chemical vapor phase deposition, wherein the support has a mounting face with a roughening, wherein, during mounting, the adhesive layer is pressed onto the mounting face, wherein the roughening penetrates the adhesive layer so that the support comes in direct contact with at least one of the carrier body or the active medium in places, and wherein a thickness of the adhesive layer is between 20 nm and 0.6 m inclusive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An optic device, a method and an assembly described herein are explained in greater detail below by way of exemplary embodiments with reference to the drawing. Elements which are the same in the individual figures are indicated with the same reference numerals. The relationships between the elements are not shown to scale, however, but rather individual elements may be shown exaggeratedly large to assist in understanding.

(2) In the figures:

(3) FIG. 1 schematically shows a method to produce an optic device;

(4) FIGS. 2-7 show exemplary sectional views of exemplary embodiments of optic devices described herein;

(5) FIGS. 8A-8C and FIGS. 9A-9C show schematic methods to produce assemblies described herein;

(6) FIGS. 10 and 11 show schematic sectional views of exemplary embodiments of optic devices described herein;

(7) FIGS. 12A-12B show a method to produce an assembly described herein; and

(8) FIG. 13 schematically explains a calculation of a thermal resistance for optic devices and assemblies described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(9) FIG. 1 shows an exemplary method to produce an optic device 1. Two reactants 81, 82 are applied from, for example, heated cups to a back side of a wafer composite of a carrier body 3 and an active medium 2. By means of a reaction between the two reactants 81, 82, an adhesive layer 4 is formed in particular by means of polymerization. As the adhesive layer 4 is formed from the vapor phase, the adhesive layer 4 can be manufactured very precisely and also to be very thin.

(10) The materials for the adhesive layer 4 could be deposited in a vacuum (e. g. 1107 torr) to a pressure up to 100 psi. The substrate temperatures during deposition are preferably ranging from room temperature to 200 C. Many other parameters could be used, too, as described in particular in the article Ayse Asatekin et al., Designing Polymer Surfaces via Vapor Deposition in Materials Today, May 2010, Vol. 13, No. 5, pages 26 to 33 and references therein.

(11) Along the dashed lines shown in FIG. 1, the wafer composite is singulated to the individual optic devices 1. Singulation is thus performed preferably after the adhesive layer 4 has been produced.

(12) FIG. 2 shows an exemplary embodiment of the optic device 1. In this case, the optic device 1 includes a carrier body 3 which can be a growth substrate 23 for a semiconductor layer sequence 21. The growth substrate 23 is a sapphire substrate, for example. The semiconductor layer sequence 21 may be based on the material system AlIInGaN.

(13) The semiconductor layer sequence 21 comprises an active zone 22, for example, a single quantum well structure or a multiple quantum well structure. In the active zone 22, light is produced in the finished optic device 1 by means of electroluminescence. Hence, the optic device 1 can be an LED chip. The active medium 2 is thus the semiconductor layer sequence 21 comprising the active zone 22.

(14) The adhesive layer 4 is applied to a side of the growth substrate 23 which is remote from the semiconductor layer sequence 21. Thus, the adhesive layer 4 is distant from the active medium 2.

(15) In the exemplary embodiment of FIG. 3, the adhesive layer 4 is applied directly to the semiconductor layer sequence 21. In this case, the semiconductor layer sequence 21 can be mechanically stable enough so that a separate carrier can be omitted. Hence, the semiconductor layer sequence 2 forms the carrier body 3 and the active zone 22 is the active medium 2 which is included in the semiconductor layer sequence 21 and, hence, in the carrier 3.

(16) As an option it is shown in FIG. 3 that a separate carrier body 3 (drawn with a dashed line) can be present at a side of the semiconductor layer sequence 21 remote from the adhesive layer 4. In this case, the semiconductor layer sequence 21 does not need to be self-supporting.

(17) In FIG. 4 it is shown that the carrier body 3 is applied with the adhesive layer 4 on one side and with a phosphor 29 on the other side. The phosphor 29 is designed to produce radiation by means of photoluminescence. Thus, the phosphor 29 is the active medium 2.

(18) The carrier body 3 is, for example, a ceramic body or a glass body. The phosphor 29 can be directly applied to the carrier body 3 or optionally is included in a matrix material like a siloxane or glass.

(19) According to FIG. 5, the phosphor 29 is present in the form of particles which are embedded in a matrix material 32. The matrix material 32, which can be a siloxane or a glass, for example, forms the carrier body 3. The phosphor 29 is located in places at surfaces of the carrier body 3 and, thus, can be in direct contact with the adhesive layer 4.

(20) As an alternative to FIG. 5, the phosphor 29 can be made of phosphor particles which can be sintered together. In this case, the matrix material can be omitted and the adhesive layer 4 can be directly applied to such a sintered phosphor 29.

(21) In FIG. 6 it is illustrated that the adhesive layer 4 is composed of a plurality of sub-layers 41, 42. There can be a sequence of first sub-layers 41 and second sub-layers 42 that are stacked one above the other in an alternating manner. Thus, the adhesive layer 4 can be a two-component adhesive and an adhesive effect can be produced by intermixing the sub-layers 41, 42, for example, by means of a mechanical process like pressing the optic device 1 to a support, not shown.

(22) According to FIG. 7, the adhesive layer 4 comprises a base layer 43 and a cover layer 44. The cover layer 44 is preferably thinner than the base layer 43. The base layer 43 can be protected by the cover layer 44 until the optic device 1 is applied to a support, not shown.

(23) The relatively complex setups of the adhesive layer 4 as shown in FIGS. 6 and 7 can also be present in all other exemplary embodiments. However, for a simplified manufacturing of the adhesive layer 4 it is preferred that the adhesive layer 4 is of a single homogeneous layer as shown, for example, in connection with FIGS. 1 to 5.

(24) In FIG. 8, a method to produce an assembly to from the optic device 1 is explained. According to FIG. 8A, an optoelectronic semiconductor chip 9, like an LED chip, is provided. Further, the optic device 1 with the adhesive layer 4 is also provided. For example, the optic device 1 in this case contains the phosphor 29 and, thus, is a conversion element.

(25) As an alternative as shown in FIG. 8B, the optic device 1 is an LED chip with the semiconductor layer sequence 21 and the adhesive layer 4. The other component that is provided is the phosphor 29. Contrary to what is shown in FIG. 8B, the phosphor 29 may also be provided with an adhesive layer 4, illustrated as a dashed line, so that there may be two of the optic devices 1.

(26) The resulting assembly to is shown in FIG. 8C. The LED chip 9 and the phosphor 29 have been firmly and permanently connected by means of the adhesive layer 4, which has a thickness, for example, of just 100 nm to 200 nm.

(27) According to FIG. 9A, the optic device 1 is an LED chip, too, that comprises the adhesive layer 4. Moreover, a support 6 with a mounting face 60 is provided. The support 6 is a part of a metallic lead frame. Preferably, the mounting face 60 is a mirror 61 for the radiation generated in the optic device 1.

(28) As illustrated in FIG. 9B, as an alternative the adhesive layer 4 is applied to the mounting face 60 which is the mirror 61. The adhesive layer 4 can be applied to the mounting face 60 in a structured manner and, thus, just in places required to mount the semiconductor chip 9.

(29) The resulting assembly to is shown in FIG. 9C. Contrary to what is shown in FIG. 9C, it is possible when coming from FIG. 9B that the adhesive layer 4 may protrude beyond side faces of the semiconductor chip 9. An electrical connection to the semiconductor chip 9 is realized, for example, by at least one bond wire 91.

(30) According to FIG. 10, the active medium 2 and the carrier body 3 are supplied with electric contact areas 5. The contact areas 5 are located on a side opposite the adhesive layer 4. Thus, the adhesive layer 4 can be electrically insulating.

(31) Contrary to that, see FIG. 11, the electric contact areas 5 and the adhesive layer 4 are located at the same side of the active medium 2. In this case it is possible that the adhesive layer 4 serves to make an electrical contact to the contact areas 5. Thus, the adhesive layer 4 is preferably electrically conductive.

(32) To achieve an adhesive layer 4 that is sufficiently electrically conductive, the polymers of the adhesive layer 4 can be electrically conductive. As an alternative or in addition, the adhesive layer may comprise a plurality of particles 45 which are made of an electrically conductive material like carbon nanotubes or silver. As the particles 45 are comparably small and, thus, an electrical conductivity is just realized in a direction perpendicular to the contact areas 5, electrical shorts between adjacent contact areas 5 can be avoided.

(33) In the method as shown in FIGS. 12A and 12B, first the optic device 1 is provided. For example, the optic device 1 is set up as illustrated in FIG. 7 above. Moreover, the support 6 is supplied. At the mounting face 60, the support comprises a roughening with a comparably low mean depth of structural elements.

(34) As illustrated in FIG. 12B, the optic device 1 is pressed onto the mounting face 60. The adhesive layer 4 is penetrated by the roughening of the mounting face 60 so that the optic device 1 and the support 6 can come in direct contact with each other in places.

(35) In FIG. 13, a calculation of a thermal resistance Rth is explained. The thermal resistance Rth essentially depends on a thickness of the respective materials and on a thermal conductivity of the respective materials. Moreover, the larger the size of a semiconductor chip, the lower the resulting thermal resistance Rth. As can be seen from FIG. 13, lower part, the total thermal resistance Rth strongly depends on the thickness of the adhesive layer as the thermal conductivity of the adhesive layer is small compared with other components of the device. Hence, when reducing the thickness of the adhesive layer 4, the total thermal resistance Rth can be significantly reduced.

(36) The calculation in FIG. 13 is based on the device Duris S5 from the manufacturer Osram Opto Semiconductors that comprises two LED chips for producing blue light with a size of 650 m650 m each.

(37) The components shown in the figures follow, unless indicated otherwise, preferably in the specified sequence directly one on top of the other. Layers which are not in contact in the figures are preferably spaced apart from one another. If lines are drawn parallel to one another, the corresponding surfaces are preferably oriented parallel to one another. Likewise, unless indicated otherwise, the positions of the drawn components relative to one another are correctly reproduced in the figures.

(38) The invention described here is not restricted by the description on the basis of the exemplary embodiments. Rather, the invention encompasses any new feature and also any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.