TWI424587B - Light emitting diodes with nanoscale surface structure and embossing molds forming nanometer scale surface structures - Google Patents

Description

Light-emitting diode having a nano-scale surface structure and imprint mold forming a nano-scale surface structure

The present invention relates to a solid-state light emitting device, and more particularly to a light-emitting diode having a high light extraction efficiency.

In a solid-state light-emitting device, in particular, a light-emitting diode (LED), for example, an epitaxial process for controlling epitaxial conditions, or a roughening process such as wet etching or dry etching, so that the light-emitting surface of the light-emitting diode has The predetermined roughness is thereby increased the light extraction rate to increase the luminance of the entire component.

Related art such as "Nitride-Based LEDs With 800 °C Grown p-AlInGaN-GaN Double-Cap Layers" (SJ Chang et al, IEEE Photonics Technolog Letters, Vol. 16, No. 6, June 2004 p. 1447 ~ 1449), using 800 The epitaxial temperature of °C allows the p-type gallium nitride to grow at a slower lateral growth rate to obtain a light-emitting diode having a rough light-emitting surface; "Increase In The Extraction Efficiency Of GaN-based Light-Emitting Diodes Via Surface Roughening" (T. Fujii et al., Applied Physics Letters Vol. 84, No. 6, p. 855-857) is applied to photoelectro-chemical (PEC) using an etchant based on potassium hydroxide. Etching to form a roughened light surface of a tapered pattern; "Integrate ZnO Nanotips On GaN Light Emitting Diodes For Enhanced Emission Efficiency" (J. Zhong et al., Applied Physics Letters 90, 203515 (2007)), discloses p-type nitridation Technique for forming a roughened surface of zinc oxide nano-needle on gallium Surgery.

On the whole, the uniformity of the roughened light surface formed by the current technology is not good, although the light extraction rate can be effectively improved, the effect is still not preferable, and the reproducibility of the roughening process is not uniform, therefore, At present, it is still not stable for the mass production of the industry.

Therefore, how to design and fabricate a light-emitting diode having an optimum light extraction rate of the light-emitting surface under the premise of stable mass production is a goal that the related field has been striving for.

Under the premise of mass production, the reproducibility of the product through the same process must be extremely high. In all current processes, the pre-designed pattern is transferred to the LED through the die imprinting to obtain the roughening. The light surface is one of the most reproducible technologies.

Therefore, the inventor conceived that the design of the light-emitting diode with the best light extraction rate must be started by this process; however, the technology of imprinting and transferring the pattern through the mold is mature, but the technology should be transferred. When the solid surface component, especially the light-emitting diode, is roughened to enhance the light extraction rate, one of the problems to be overcome is the design of the pattern, and the second is that when the scale of the pattern to be transferred is reduced to the nanometer scale. The pattern designed on the mold and the transferred pattern will be limited by the process and will be deformed. As a result, the light extraction rate simulated during the design will be different from the actual product, and the reservation will not be achieved. The goal.

The inventor believes that to solve the problem that the pattern to be transferred is limited by its own scale and process limitation, it can be from the direction of the irregular pattern. At the beginning, the error of deformation of the transfer pattern is offset by the irregular pattern, but the irregular pattern must be arranged in an orderly manner, so that the light extraction rate can be substantially improved under the premise of high reproducibility.

Based on the above ideas, the inventors conducted a majority of experiments, and obtained the present invention to provide a light-emitting diode having a nano-scale surface structure having an optimum light extraction rate.

Further, the present invention provides an imprint mold suitable for use in a nanoimprinting machine to form a nano-scale surface structure of a solid element.

Thus, the present invention has a nano-scale surface structure of a light-emitting diode comprising a light-emitting body and a nano-scale surface structure.

The light-emitting body generates light by a photoelectric effect when energized, and has a light-emitting surface for emitting light to the outside.

The nano-scale surface structure comprises a plurality of grooves formed on the light-emitting surface and arranged in a concentric ring with a plurality of inner diameters in a series of equal numbers, the cross-sectional shapes of the grooves being mostly irregular and having a size in the nanometer scale The pattern, and the spacing between adjacent two grooves belonging to the same concentric ring is in the nanometer scale range.

In addition, the present invention relates to an imprinting mold for forming a nano-scale surface structure, which is suitable for a nano-imprinting machine to form a corresponding patterned film on a thermosetting polymer coated on the surface of the wafer, and then the state of the patterned film. The sample is transferred to the surface of the wafer, and the imprinting mold forming the nano-scale surface structure comprises a mold body and a structural pattern.

The mold body is detachably coupled to the nanoimprinting machine and has an embossed surface.

The structural pattern includes a majority formed on the embossed surface and arranged in a plurality a bump of a concentric ring of equal difference series, the cross-sectional shape of the bumps being a rectangle having a size irregular in the nanometer scale, and the spacing of adjacent two bumps belonging to the same concentric ring is in the nanometer Scale range.

The utility model has the advantages that: in the premise of satisfying mass production, an imprinting mold having a single structural pattern which is irregular and has a size of a nanometer, but a plurality of concentric rings arranged with an inner diameter of an arithmetic number are arranged, The light-emitting diode having the corresponding nano-scale surface structure is formed by the imprint transfer method, and the nano-scale surface structure of the pattern can substantially improve the light extraction rate of the light-emitting diode, thereby effectively improving the overall light emission of the component. brightness.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Before the present embodiment is described in detail, it should be noted that the following description and illustrations are all illustrated by a vertical injection type LED structure, and the electrodes are not shown, but have ordinary fields in the art. The skilled person can easily understand the technical idea of the present invention from the following description, and apply the present invention to various types of light-emitting diodes, and even similar solid-state light-emitting elements.

Referring to FIG. 1 and FIG. 2, a preferred embodiment of the light-emitting diode 2 having a nano-scale surface structure comprises a light-emitting body 3 and a nano-scale surface structure 4, which has a higher light extraction rate performance. The overall brightness is higher.

The illuminating body 3 has a 矽 substrate 31 and an epitaxial film 32 disposed on the ytterbium substrate 31 and epitaxially formed by a gallium nitride based semiconductor material. The film 32 includes a p-n junction 33 (p-n junction) which generates light by a photoelectric effect upon energization, and a light-emitting surface 34 which is supplied to the outside by a light supply.

Referring to FIG. 3 and FIG. 4, the nano-scale surface structure 4 is formed by using an imprint transfer technology (relevant process is required), and a plurality of concentric rings are formed on the light-emitting surface 34 and arranged in the same center. a groove 41 of 100, the cross-sectional shape of the grooves 41 is a pattern with a majority of irregularities and a size in the nanometer scale, and the spacing between adjacent two grooves 41 belonging to the same concentric ring 100 is in the nanometer scale range. The inner diameter of the equivalent core ring 100 has a tolerance of 50 nm to 1000 nm.

In this example, the equivalent core ring 100 is a concentric ring with an inner diameter tolerance of 200 nm, and the cross-sectional shape of the grooves 41 is an elongated shape having an unequal length but an approximate width, and the largest inner diameter is 50 nm. ~1000nm, the depth is 50nm~1000nm.

Referring to FIG. 5, FIG. 5 is a view showing a preferred embodiment of the light-emitting diode 2 having the nano-scale surface structure 4 of the present invention as compared with the conventional light-emitting diode (light-emitting diode of the non-rough surface of the light-emitting surface). Comparing the current-forward voltage, it can be seen from the figure that the preferred embodiment of the above-described light-emitting diode 2 having the nano-scale surface structure 4 of the present invention is similar to the electrical requirements and electrical performance of the existing light-emitting diode. .

Referring to FIG. 6, FIG. 7, and FIG. 8, FIG. 6 is a comparison result of the current-light output intensity of the preferred embodiment of the light-emitting diode 2 having the nano-scale surface structure 4 of the present invention and the conventional light-emitting diode. Figure 7 is a comparison of the spectral performance, and Figure 8 is a comparison of the light output intensities in each direction. From the comparison of the three figures, the light-emitting diode 2 having the nano-scale surface structure 4 of the present invention is indeed Compared with the existing light-emitting diodes, the nano-scale surface structure 4 has higher light extraction rate and overall light-emitting brightness performance.

The preferred embodiment of the above described light-emitting diode 2 of the present invention having a nano-scale surface structure 4 will be more clearly understood in the following detailed description of the mold and the manufacturing process. It should be further noted that the following descriptions are all descriptions for making a single die in accordance with the above description. Those who have a slight semiconductor process concept can easily know the actual mass production in wafers from the following description. Production process.

Referring to FIG. 9 and FIG. 10, firstly, an imprinting mold 5 suitable for a nano imprinting machine (not shown) is prepared. The imprinting mold 5 includes a detachable coupling in the nano imprinting machine and has a The mold body 51 of the embossed surface 511, and a structural pattern 52 formed on the embossed surface 511.

The structure pattern 52 corresponds to the nano-scale surface structure 4 of the preferred embodiment of the above-described light-emitting diode 2 having the nano-scale surface structure 4 of the present invention, and includes a plurality of concentric surfaces formed on the embossed surface 511 and arranged in the same center to form a plurality of concentric portions. The bumps 521 of the ring 100 correspond to the grooves 41 of the nano-scale surface structure 4 to be formed, and the cross-sectional shapes of the bumps 521 are rectangular blocks having irregularities and sizes in the nanometer scale, and belong to The spacing between adjacent two bumps 521 of the same concentric ring 100 is in the nanometer scale range, and the inner diameter of the equivalent core ring 100 has a tolerance of 50 nm to 1000 nm.

Corresponding to the preferred embodiment of the present invention, the equivalent core ring 100 is a concentric ring, and the inner diameter tolerance is 200 nm, and the cross-sectional shape of the bumps 521 is a rectangle having different lengths but the same width, and the The length of these bumps is 50nm~1000nm, the width is 50nm~1000nm, and the height is 50nm~ 1000nm.

Then, the illuminating body 3 of the structure of the illuminating diode 2 is fabricated by a general process; then, a layer of cerium oxide (SiO ₂ ) is deposited on the illuminating surface 34 of the illuminating body 3 by chemical vapor deposition, and then a very thin heat is applied. The polymer is solidified; then, the nano-imprinting machine provided with the imprinting mold 5 is used, and the thermosetting polymer is heated and pressurized by the imprinting mold 5 to transfer the structural pattern 52 of the imprinting mold 5 to heat. On the solid polymer; the pattern of the thermosetting polymer is transferred to the cerium oxide by reactive ion etching (RIE): Finally, an inductively coupled plasma etching method is used to form a patterned cerium oxide layer. The mask is isotropically etched to the illuminating body 3, and is completed by etching and the remaining cerium oxide structure is removed by BOE (deoxidation etching solution), that is, the light-emitting diode 2 having the nano-scale surface structure 4 of the present invention is completed. Preferred embodiment.

In this process, it should be particularly noted that since the bump 521 of the imprinting mold 5 has a very small scale, after being embossed on the thermosetting polymer, the rectangular recess 41 which should be formed correspondingly should be deformed substantially. The stripe of the rectangle (that is, the four inner corners of the rectangle can no longer be maintained at 90 degrees and passivated), after which a series of etching processes will make the angle of the pattern more gelatinized, and finally, the length as shown in Fig. 3 and Fig. 4 is obtained. Strip-shaped groove 41; and in particular, although the design pattern of the original imprinting mold 5 is a rectangular block, the pattern of the final product is the elongated groove 41, but the design is initially considered to offset the transfer by the irregular pattern. The pattern is deformed by the error, and the irregular patterns are arranged in an orderly arrangement (the inner diameter is equal to the number of columns) of concentric rings 100, so that the light extraction rate of the element can be substantially improved.

In addition, it should be emphasized that the arrangement of the grooves 41 of the nano-scale surface structure of the light-emitting diode having the nano-scale surface structure can be as shown in FIG. 11, and the radius of the equivalent-heart ring 100 is much larger than that of the wafer. The length of the side is such that the grooves 41 on the light-emitting surface of the wafer are arranged to look like a parallel line arrangement, or may be arranged on a single wafer to have a plurality of different ones as shown in FIGS. 12 and 13 . The center of the concentric ring is 100, and the center of the equivalent ring 100 can also be regular (as shown in FIG. 12) or irregularly arranged (as shown in FIG. 13), which can substantially improve the light extraction of the component. In addition, according to the calculation, the arrangement of concentric polygonal rings (for example, hexagons, octagons, etc.) can also substantially improve the light extraction rate of the components, due to the numerous ordered arrangements of these rules, here No more detailed examples.

In summary, the present invention does use an imprint transfer method, and under the premise of high reproducible mass production, a structural pattern of an imprint mold having a scale on a nanometer scale is designed, and transferred to a light-emitting body to form a nanometer. The level surface structure, by a single single irregular pattern, but arranged in an ordered concentric ring pattern, offsets the error that the deformation of the process will occur and the actual product light extraction rate is not high, providing a true high light. The light-emitting diode having a nano-scale surface structure with a take-out rate achieves the inventive object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

100‧‧‧Concentric Ring

2‧‧‧Lighting diode

3‧‧‧Lighting body

31‧‧‧矽 substrate

32‧‧‧Elevation film

33‧‧‧p-n junction

34‧‧‧Glossy

4‧‧‧Nano-scale surface structure

41‧‧‧ Groove

5‧‧‧ Imprinting mold

51‧‧‧Mold body

511‧‧‧embossed surface

52‧‧‧Structural pattern

521‧‧‧ bumps

Figure 1 is a plan view showing the present invention having a nano-scale surface structure A preferred embodiment of a light-emitting diode; FIG. 2 is a cross-sectional view of the preferred embodiment of the light-emitting diode of the present invention having a nano-scale surface structure; FIG. 3 is a photomicrograph of an atomic force microscope. 1 is a nanometer surface structure; FIG. 4 is an electron micrograph, which assists in explaining one nanometer surface structure of FIG. 1; FIG. 5 is a current-forward voltage curve, illustrating that the present invention has Figure 6 is a current-light output intensity curve illustrating the light-emitting diode of the present invention having a nano-scale surface structure and the existing one. The light output performance of the light-emitting diode; FIG. 7 is a spectral graph illustrating the spectrum of the light-emitting diode having the nano-scale surface structure of the present invention and the existing light-emitting diode; FIG. 8 is a light output intensity in each direction The figure illustrates the light output intensity of the light-emitting diode having a nano-scale surface structure and the existing light-emitting diode of the present invention; FIG. 9 is a perspective view illustrating the light-emitting two for fabricating the nano-scale surface structure of the present invention. Polar body Figure 10 is an electron micrograph showing the structure of the imprint mold of Figure 9; Figure 11 is a plan view showing the light-emitting diode of the present invention having a nano-scale surface structure. An ordered arrangement of another groove of the nanoscale surface structure of the body; Figure 12 is a top plan view showing another groove-ordered arrangement of the nano-scale surface structure of the light-emitting diode having a nano-scale surface structure of the present invention; and Figure 13 is a plan view showing the present invention having a nai A further arrangement of the grooves of the nano-scale surface structure of the light-emitting diode of the rice-scale surface structure.

100‧‧‧Concentric Ring

2‧‧‧Lighting diode

3‧‧‧Lighting body

31‧‧‧矽 substrate

32‧‧‧Elevation film

33‧‧‧p-n junction

34‧‧‧Glossy

4‧‧‧Nano-scale surface structure

41‧‧‧ Groove

Claims (10)

A light-emitting diode having a nano-scale surface structure, comprising: a light-emitting body, which generates light by photoelectric effect when energized, and has a light-emitting surface for emitting light to the outside; and a nano-scale surface structure, including majority formation a groove on the light-emitting surface and arranged in a concentric ring with a plurality of inner diameters in a series of equal numbers, the cross-sectional shape of the grooves being a pattern having a plurality of irregularities and having a size within a nanometer scale, and belonging to the same concentric ring The spacing between adjacent grooves is in the nanometer range. The light-emitting diode having a nano-scale surface structure according to claim 1, wherein the inner diameter of the equivalent core ring has a tolerance of 50 nm to 1000 nm. The light-emitting diode having a nano-scale surface structure according to claim 2, wherein the grooves have a long cross-sectional shape and a maximum inner diameter of 50 nm to 1000 nm and a depth of 50 nm. 1000nm. A light-emitting diode having a nano-scale surface structure according to claim 3, wherein the equivalent core ring is a concentric ring. A light-emitting diode having a nano-scale surface structure according to claim 3, wherein the equivalent core ring is a concentric equilateral polygonal ring. An imprinting mold for forming a nano-scale surface structure, which is suitable for a nano-imprinting machine to form a corresponding pattern film on a thermosetting polymer coated on the surface of the wafer, thereby transferring the pattern of the pattern film to the The wafer surface, the imprinting mold forming the nano-scale surface structure comprises: a mold body detachably coupled to the nano embossing machine and having a embossed surface; and a structural pattern including a plurality of bumps formed on the embossed surface and arranged in a concentric ring with a plurality of inner diameters in a series of equal numbers The cross-sectional shape of the bumps is a rectangle having irregularities and a size within a nanometer scale, and the pitch of adjacent two bumps belonging to the same concentric ring is in the nanometer scale range. The imprinting mold for forming a nano-scale surface structure according to claim 6, wherein the inner diameter of the equivalent core ring has a tolerance of 50 nm to 1000 nm. The imprinting mold for forming a nano-scale surface structure according to claim 7, wherein the cross-sectional shape of the bumps is 50 nm to 1000 nm in length, 50 nm to 1000 nm in width, and heights of the bumps. 50nm~1000nm. An imprint mold for forming a nano-scale surface structure according to claim 8 of the patent application, wherein the equivalent core ring is a concentric ring. An imprinting mold for forming a nano-scale surface structure according to the invention of claim 8, wherein the equivalent core ring is a concentric equilateral polygonal ring.