TWI722712B - Light-emitting device substrate and manufacturing method - Google Patents

Abstract

The embodiment of the present invention can provide a buried metal pattern formed on the surface of a sapphire substrate, and a refractive layer with a lower refractive index than that of the sapphire substrate is formed on the top of the metal pattern to manufacture a light emitting device substrate. Other embodiments of the present invention may provide a method for manufacturing a light-emitting device substrate: a stage of forming a buried metal pattern on the substrate, a stage of forming a refractive layer covering the substrate and the metal pattern, and a stage of forming a photoresist layer on the refractive layer In the exposure stage of irradiating the back of the substrate with UV light, developing and removing the partial area of the photoresist layer and exposing the partial area of the refractive layer, and etching the remaining photoresist layer on the refractive layer and exposing the sapphire substrate.

Description

Light-emitting device substrate and manufacturing method

The present invention relates to a light-emitting device substrate and a manufacturing method thereof, in particular to a light-emitting device substrate and a light-emitting device substrate for forming a buried metal pattern and a refractive layer on a sapphire substrate to increase the reflectivity of light and the luminous efficiency of the LED chip.其制造方法。 Its manufacturing method.

LED (Light Emitting Diode: Light Emitting Diode) is a connection diode of P-type semiconductor and N-type semiconductor connection-PN, which converts electrical signals into visible light, infrared, ultraviolet and other light forms. The light-emitting diode is connected to the P-type and N-type semiconductors, and the current is delivered to the device through voltage. The positive hole of the P-type semiconductor moves in the direction of the N-type semiconductor. On the contrary, the electrons of the N-type semiconductor move in the direction of the P-type semiconductor. Move, the described hole and electron move to the PN junction.

The PN connection part, that is, the positive hole and the electrons in the active layer recombine to produce light, and the moving electrons drop from the conduction band to the valence band, and combine with the positive hole at the same time, the conduction band and valence generated at this time The energy level of the belt is different, and the different energy will be released, and it will be released in the form of light.

Light-emitting diodes are environmentally friendly products with low voltage, long life, and low price. They can be used to replace indicators, fluorescent lights, and colored lights. At present, due to the development of industrial technology, it is used in the field of display, automobile headlights, projectors, communication devices and many other aspects.

Most of the specific structure of the LED adopts an epitaxial method, which is grown on the substrate in the order of the N-type layer, the active layer, and the P-type layer. GaN-based LEDs are generally grown on Si (silicon), SiC (silicon carbide) and sapphire substrates, with sapphire substrates being the most common application.

At present, the most widely used sapphire patterned substrate technology (PSS: Patterned Sapphire Substrate) can reduce the dislocation density in the epitaxial layer and improve the internal quantum efficiency of the LED through the scattering of the PSS pattern. The traditional PSS technology uses photolithography and etching to form multiple microscopic patterns on the sapphire surface.

For example, on the surface of a sapphire with a (0001) crystal orientation, a convex cone pattern with a fixed periodic structure is formed, leaving a certain area of (0001) crystal plane between the convex cones. There is a certain selective growth mechanism between the conical surface of the protrusion and the (0001) crystal plane between the cone.

That is, during epitaxial growth, the probability of nuclear growth on the (0001) crystal plane between the cones of the protrusions is higher than that on the surface of the conical protrusions. The epitaxial layer on the upper part of the conical protrusions is generally formed in the lateral direction. The epitaxial growth on the PSS substrate has a lateral growth effect, can reduce the dislocation density of the epitaxial layer, and can improve the internal quantum efficiency of the LED using the PSS substrate. In other respects, because the microstructure of the PSS substrate surface has a certain diffusion and scattering effect on the emitted light of the LED, which can avoid the effect of total reflection, the PSS substrate can also improve the luminous efficiency of the LED.

These traditional PSS technologies have many shortcomings. First of all, no matter whether the wet method or the dry method is used, the processing of sapphire is very difficult, which will not only affect the yield of traditional PSS products, but also increase the manufacturing cost. Second, because the growth selectivity between the sapphire conical protrusion surface and the (0001) crystal plane between the conical protrusions is not obvious, if the area of the (0001) crystal plane between the conical protrusions is too small, the Nodules are formed on the surface of the protrusions, and the direction of the nodules formed on the surface of the conical protrusions is different from the direction of the crystal nuclei formed on the (0001) crystal plane between the conical protrusions, so it is easy to generate many crystals. Third, the refractive index of the sapphire substrate Relatively high, about 1.8, so even if a protrusion structure is formed on its surface, the diffusion and scattering effect of LED light is not optimal, and it will have a great impact on the improvement of luminous efficiency.

In view of this, the inventor proposes the following technical solutions.

The main purpose of the present invention is to provide a light emitting device substrate, including: a sapphire substrate; a plurality of metal patterns, which are buried metal patterns formed on the surface of the substrate; and a plurality of refraction layers, respectively formed on top of the metal patterns, It has a lower refractive index than the sapphire substrate.

According to an embodiment of the present invention, the metal pattern has a curved surface convex toward the substrate.

According to an embodiment of the present invention, the higher the refractive layer is, the smaller the cross-sectional area is.

According to an embodiment of the present invention, the refractive layer includes silicon dioxide (SiO2).

According to an embodiment of the present invention, the material of the metal pattern includes gold (Au), silver (Ag), cobalt (Co), iron (Fe), copper (Cu), platinum (Pt), palladium (Pd), aluminum ( Al), chromium (Cr), nickel (Ni) or a mixture of multiple metals.

According to an embodiment of the present invention, the thickness of the refractive layer is greater than the thickness of the metal pattern.

According to an embodiment of the present invention, the metal pattern is formed on the top of the sapphire substrate.

According to an embodiment of the present invention, the refractive layer covers the metal pattern and part of the sapphire substrate.

According to an embodiment of the present invention, the sapphire substrate is formed with a plurality of protrusions higher than the surface of the metal pattern.

According to an embodiment of the present invention, a method for manufacturing a light-emitting device substrate at the stage of forming the buried metal pattern on the substrate includes the following steps: the stage of forming the substrate and the refractive layer covered on the metal pattern; A stage of forming a photoresist layer; an exposure stage of irradiating UV light on the back of the substrate; a developing stage of removing a part of the photoresist layer to expose a part of the refractive layer; and etching the photoresist remaining on the refractive layer Layer and exposing the sapphire substrate stage.

According to an embodiment of the present invention, the method for manufacturing a light-emitting device substrate at the stage of forming the buried metal pattern includes the following steps: forming the photoresist layer on the substrate; exposing a part of the substrate through exposure and development to form A stage of a plurality of photoresist patterns; a stage of etching the exposed substrate; and a stage of forming the metal pattern in an area of the substrate after the etching.

According to an embodiment of the present invention, the etching stage is used to etch and expose the sapphire substrate.

According to an embodiment of the present invention, the etching stage is used to etch the refractive layer, and the higher the refractive layer is, the smaller the cross-sectional area is.

Fig. 1 is a structural diagram of a light-emitting device substrate according to an embodiment of the present invention. The substrate 100 used in the light emitting device according to this embodiment may include a sapphire substrate 110, and the metal pattern 120 may be formed on the sapphire substrate 110. Since the metal pattern exists above the sapphire substrate 110, the irregular bonding surface between the metal pattern 120 and the sapphire substrate 110 can minimize light loss.

The refractive layer 130 can be formed and cover the surface of the metal pattern 120. The refractive layer 130 may include silicon dioxide (SiO2). The thickness of the refractive layer 130 may be thicker than the metal pattern 120. The thickness of the refractive layer 130 may be 50 nm to 3 um. The refractive layer 130 may be formed to cover the upper part of the buried metal pattern 120 and part of the sapphire substrate 110. In this embodiment, the refraction layer 130 is formed of silicon dioxide (SiO2) to prevent oxygen passivation of the metal pattern 120, and a metal pattern with a convex curved surface toward the substrate is used to change the angle of reflected light and control the light. The effect of concentration.

In this embodiment, as the metal pattern 120 and the refraction layer 130 are formed on the sapphire substrate 110, the refractive index of silicon dioxide (SiO ₂ ) is 1.45 less than the refractive index of sapphire 1.76, which can effectively increase the light scattering effect of the substrate, thereby improving the LED chip’s performance Luminous efficiency. The higher the refractive layer 130 is, the smaller the cross-sectional area is. For example, polygonal pyramid shapes such as cones, triangular pyramids, and quadrangular pyramids, and dome shapes, etc., can be embodied in various forms.

Fig. 2 is a structural view of a light-emitting device substrate according to another embodiment of the present invention.

2, the substrate 200 used in the light-emitting device according to this embodiment may include a sapphire substrate 210, a protrusion 211 formed on the surface of the sapphire substrate 210, a buried metal pattern 220 is formed on the surface of the substrate 200, and the upper part of the metal pattern 220 is covered. Refractive layer 230.

Compared with the embodiment in FIG. 1, the shape of the protruding part 211 is added, and only this part will be described. The protruding part 211 may be a part of the sapphire substrate 210. That is, the protruding portion 211 may be a pattern formed on the surface of the sapphire substrate 210 after the sapphire substrate 210 is etched. This method processes the surface of the sapphire substrate 210 to form the protrusion 211, which has the advantage of stably growing the compound on the surface of the sapphire substrate 210.

Fig. 3 is a flowchart of a method for manufacturing a light-emitting device substrate according to an embodiment of the present invention.

3, it includes a stage (a) of forming a buried metal pattern above the substrate, a stage (b) of forming a refractive layer covering the substrate and the metal pattern, and a stage (c) of forming a photoresist layer above the refractive layer , From the UV light exposure stage (d) on the back of the substrate, the photoresist layer is partially removed, and the refractive layer is exposed (e), the remaining photoresist layer on the refractive layer is etched and the sapphire substrate is exposed ( f, g).

The process of etching the sapphire substrate 310 can be performed at the stage (a) of forming the buried metal pattern on the substrate. The process of forming the metal pattern is described in detail in FIG. 4. According to the light-emitting device substrate of this embodiment, the metal pattern 320 can be formed on the surface of the sapphire substrate 310 in a buried form to form a convex curved surface toward the sapphire substrate 310.

The stage (b) of forming the refractive layer covering the metal pattern 320 may form the refractive layer 301 to cover the sapphire substrate 310 and the buried metal pattern 320 on the sapphire substrate. The refractive layer 301 may include silicon dioxide (SiO2). In this way, the refractive layer 301 can be formed using a process such as physical vapor deposition (Sputtering) or chemical vapor deposition (Chemical Vapor Deposition) PECVD (Plasma Enhanced CVD). The thickness of the refractive layer 301 may be thicker than the film-shaped metal pattern 320.

In the stage (c) of forming the photoresist layer, the photoresist layer 350 can be formed on the refractive layer 301. When the photoresist used in this embodiment is exposed to ultraviolet light, the area exposed to the ultraviolet light is a positive photoresist (Positive Photoresist) that can be removed by a developing process. The photoresist layer 350 can be coated using a spin coater. The photoresist layer 350 can be coated with a thickness of 1 um or more.

In the exposure stage (d), UV light is irradiated to the entire sapphire substrate 310 from the backside of the sapphire substrate 310. In the general exposure process, a mask or a reticle with a specific pattern is used as a shield to create a target pattern. In this embodiment, since UV light is irradiated to the entire sapphire substrate 310 from the back of the sapphire substrate 310, the metal pattern 320 can function as a photomask at this time. Therefore, according to the presence or absence of the metal pattern 320 as a shield, the photoresist layer 350 can be divided into an area 351 that is not exposed under UV light and an area 352 that is exposed under UV light.

As described above, during the development process of the area 352 and the area 351 that are not exposed under the UV light, part of the photoresist and the developing solution will undergo a chemical reaction and be removed. In this implementation, because the positive photoresist is used for exposure, the area 352 exposed under the UV light is removed during the development process, but the area 351 not exposed by the UV light can remain. The area reserved by the development process can be used for subsequent processes.

In this way, because this embodiment does not use another mask plate or lithography plate, there is no additional cost when designing or manufacturing the lithography plate, and the photolithography process does not require expensive equipment such as an exposure machine (Stepper or Aligner), that is, It can be exposed and developed.

In the developing stage (e), a part of the area can be removed by a chemical reaction between the developing solution and the photoresist layer 350. In this embodiment, a positive photoresist is used, the area 352 exposed under the UV light during the exposure process is removed during the development process, and the area 351 not exposed under the UV light can be left. Through the development process, a buried metal pattern 320 is formed on the sapphire substrate 310, and a refractive layer 301 covering the metal pattern 320 and the sapphire substrate 310 is formed, and a photoresist layer 351 corresponding to the metal pattern 320 is formed on the refractive layer 301. .

In stage (f, g), an etching process is performed to etch the photoresist layer 351 and the refraction layer 301 on the refraction layer. The photoresist layer 351 is the area 351 that is not exposed under UV light. The etching process uses dry etching, and the etching process includes reactive ion etching (RIE), inductively coupled plasma (ICP), or TCP (Transformer Coupled Plasma) plasma etching. The etching gas used can be boron trichloride (BCl ₃ ) or chlorine (Cl ₂ ) or the like. The etching time, cavity pressure, temperature and other process parameters can be selected according to the expected pattern morphology, and the corresponding etching parameters can be selected to achieve a variety of pattern morphologies. At this stage, etching is performed until the surface of the sapphire substrate 310 is exposed.

After the etching process is completed, the structure of the sapphire substrate 310 with the buried metal pattern 320 and the silicon dioxide (SiO ₂ ) refractive layer 330 on it is completed. In particular, in this embodiment, the refraction layer 330 may cover the entire buried metal pattern 320, or even cover a part of the sapphire substrate 310 area.

In this embodiment, the structure of the refractive layer 330 is such that the cross-sectional area becomes smaller as it goes upward. The structure of the refractive layer 330 may be a cone, a triangular pyramid, a quadrangular pyramid, and the like. In addition, this gradual cross-section structure can be achieved by adjusting the etching recipe during the etching process.

After the light-emitting component substrate manufactured in this embodiment, the sapphire substrate 310 is formed with a curved metal pattern 320 protruding toward the substrate, and a refraction layer 330 formed on the metal pattern 320 to achieve the effect of changing the angle of reflected light. By controlling the concentration of light, the light extraction efficiency can be improved. In addition, since the refractive layer 330 covers the metal pattern 320, the metal pattern 320 can be prevented from passivation.

4, FIG. 4 is a flowchart of a process of forming a metal pattern according to an embodiment of the present invention.

In the stage (a) of forming a photoresist layer on the substrate, the photoresist layer 460 can be coated on the sapphire substrate 410. The photoresist layer can generally be formed by using a spin coater, and the thickness is above 1um. In this embodiment, the photoresist can be a positive photoresist. During the exposure process, the area exposed by UV light can be removed by the development process.

The stage (b) of forming the photoresist pattern can be carried out through exposure and development processes. To expose the photoresist layer 460, it is necessary to use a mask or a reticle with a certain shape and size of a specific pattern for exposure. The shape of the photomask can have various patterns. The exposure machine used in this embodiment may use a stepper. Then, when going through the photolithography pattern exposure process, only the photoresist in the area not irradiated by the UV light is retained, and the photoresist in the area irradiated by the UV light can be removed. After the development process, a photoresist pattern 461 is formed on the sapphire substrate 410, and a part of the sapphire substrate 410 is exposed at the same time.

In the etching stage (c), a groove may be formed in the exposed area of the sapphire substrate 410 through an etching process. In this embodiment, the etching process can be performed through wet etching (Wet Etch). Using wet etching isotropic etching (Isotropy Etch) characteristics is easier to form a curved surface than dry etching (Anisotropy Etch). As for the etching solution, one of sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), 4H ₃ PO ₄ +4CH ₃ COOH+HNO ₃ +H ₂ O, or a mixture of several solutions. The proportion of the etching solution, the etching time and the process temperature, etc., can be formulated according to the shape of the groove on the substrate to be formed in this implementation. At this stage, the non-photoresist area on the sapphire substrate 410 forms a groove with a curved surface. Although the photoresist pattern 461 formed on the sapphire substrate 410 is partially etched, it has not been completely removed. The photoresist pattern 461 remaining on the substrate can be used as a shielding layer of the sapphire substrate 410. On the surface of the sapphire substrate 410, only the etched part of the surface can form the metal pattern 420.

In the step (d) of forming the metal pattern, the groove of the sapphire substrate can form the metal pattern 420 after etching. The material of the metal pattern 420 may include gold (Au), silver (Ag), cobalt (Co), iron (Fe), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), chromium (Cr ), one of nickel (Ni), or a mixture of several metals. To form the metal pattern 420, an electron beam evaporation system (Electron-beam Evaporation System) can be used to form a metal layer by depositing metal particles. To form a large amount or thicker metal layer, a sputtering method can be used. In this embodiment, the metal pattern 420 can be formed to have a thickness of 5 nm to 200 nm. In this process stage, a metal pattern 420 can be formed on the surface of the groove formed on the sapphire substrate 410, and at the same time, a metal layer is also formed on the photoresist pattern 461 remaining on the sapphire substrate 410.

In this embodiment, the step (e) of removing the photoresist pattern 461 remaining on the substrate may be included. By removing the photoresist pattern 461, the substrate in contact with the photoresist layer can be directly exposed. The metal pattern can be formed to have a curved surface convex toward the substrate. The metal pattern formed in this form can change the reflection angle of light and control the concentration of light.

The above description mentions the preferable implementation and implementation form of this invention. Senior partners in this technical field should abide by the ideas and provisions of the field of this invention. In this field, the invention is within the scope specified in the scope of the following patent application: it is understood that this invention can be modified and changed in various ways. For example, the material, shape, and thickness of the refractive layer of the metal pattern can be embodied in a variety of ways. The technical idea or prospect of this invention is not a simple explanation of this embodiment. Therefore, the significance of this transformation discussion is far-reaching and is worthy of our deep consideration.

Only the above are only preferred embodiments of the present invention, and are not used to limit the scope of implementation of the present invention. Therefore, all equivalent changes or modifications made in accordance with the characteristics and spirit of the application scope of the present invention shall be included in the patent application scope of the present invention.

100...substrate 110...Sapphire substrate 120...Metal graphics 130...Refracting layer 200...substrate 210...Sapphire substrate 211...protruding part 220...Metal graphics 230...Refracting layer 310...Sapphire substrate 320...Metal graphics 330...Refracting layer 301...Refracting layer 350...photoresist layer 351...Area not exposed under UV light 352...Area exposed under UV light 410...Sapphire substrate 420...Metal graphics 460...photoresist layer 461...Photoresist pattern

Fig. 1 is a structural view of a light-emitting device substrate according to an embodiment of the present invention; 2 is a structural view of a light-emitting device substrate according to other embodiments of the present invention; 3 is a flowchart of a method for manufacturing a light-emitting device substrate according to an embodiment of the present invention; Fig. 4 is a flow chart of a process of forming a metal pattern according to an embodiment of the present invention.

100...substrate 110...Sapphire substrate 120...Metal graphics 130...Refracting layer

Claims (8)

A light-emitting device substrate includes: a sapphire substrate; a plurality of metal patterns, which are buried metal patterns formed on the surface of the substrate; and a plurality of refraction layers, which are respectively formed on the top of the metal pattern and have a refractive index higher than that of the sapphire substrate A lower refractive index; wherein the method for manufacturing a light-emitting device substrate at the stage of forming the buried metal pattern on the sapphire substrate includes the following steps: the stage of forming the substrate and the refractive layer covered on the metal pattern; the refractive layer The first stage of photoresist layer formation; the exposure stage of irradiating UV light on the back of the substrate; the development stage of removing part of the photoresist layer to expose part of the refractive layer; and etching the remaining part of the refractive layer The photoresist layer and the stage where the sapphire substrate is exposed. The light-emitting device substrate according to claim 1, wherein the metal pattern has a curved surface convex toward the substrate. The light-emitting device substrate according to claim 1, wherein the higher the refractive layer is, the smaller the cross-sectional area is. The light-emitting device substrate according to claim 1, wherein the refractive layer comprises silicon dioxide (SiO ₂ ). The light-emitting device substrate according to claim 1, wherein the material of the metal pattern includes gold (Au), silver (Ag), cobalt (Co), iron (Fe), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), chromium (Cr), nickel (Ni), or a mixture of multiple metals. The light-emitting device substrate according to claim 1, wherein the metal pattern is formed on the sapphire substrate, and the sapphire substrate is formed with a plurality of protruding surfaces higher than the surface of the metal pattern. The light-emitting device substrate according to claim 1, wherein the refractive layer covers the metal pattern and part of the sapphire substrate, and the thickness of the refractive layer is greater than the thickness of the metal pattern. The light-emitting device substrate according to claim 1, wherein the method of manufacturing the light-emitting device substrate at the stage of forming the buried metal pattern comprises the following steps: forming the photoresist layer on the substrate; exposing the light-emitting device through exposure and development A stage of forming a plurality of photoresist patterns in a partial area of the substrate; a stage of etching the exposed substrate; and a stage of forming the metal pattern in a substrate area after the etching.

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