CN107482030A - Micro LED device and manufacturing method thereof - Google Patents

Abstract

The invention provides a micro-LED device and a manufacturing method thereof, which uses plasma to directly etch an epitaxial wafer to manufacture a micron-scale LED element without transferring the LED element, wherein the substrate does not need to be peeled off, but holes are directly opened inside the substrate to form The through hole, the metal back plate as the negative electrode passes through the through hole and directly contacts the epitaxial wafer. When making the through holes in the substrate, the combination of vertical multiple stealth cutting and laser scribing is used to make the through holes, which is simple and easy to operate. In the present invention, the metal contact located on the outer periphery of the transparent upper cover is designed as the positive pole, and the positive and negative poles are directly connected to realize point-controlled LED components to emit light, thereby eliminating the need for wire bonding and transfer operations on micron-sized small-sized LED components.

Description

Micro LED device and manufacturing method thereof

technical field

The invention belongs to the field of micro-LED devices, and in particular relates to a micro-LED device manufactured by epitaxial-level welding and a manufacturing method thereof.

Background technique

The current GaN chip manufacturing process is to first cover the core grain pattern on the epitaxial wafer, and then etch and plate the electrodes. Finally, individual core particles are split out for use. The process flow is long and complicated, and with the increase of the process, the relative risk of abnormality also increases.

At present, the commonly used displays are often LCD displays, and OLED displays are more advantageous, but the pixel distances are all at the millimeter level, which cannot be achieved at the micron level. And MicroLED can reduce the pixel distance of the display to the micron level. Micro LED display, that is, LED miniaturization and matrix technology. It refers to a high-density micro-sized LED array integrated on a chip. Micro LED has the characteristics of high efficiency, high brightness, high reliability, and fast response time. It also has the characteristics of self-illumination without backlight, and has the advantages of energy saving, simple mechanism, small size, and thin profile.

Currently commonly used Micro LED display manufacturing processes include three categories:

(1) Chip-level welding, that is, to directly cut the LED into micron-level Micro LED chips (including epitaxial film and substrate), and use SMT technology or COB technology to bond the micron-level Micro LED chips to the display one by one on the substrate.

(2) Epitaxial welding, that is, using inductively coupled plasma ion etching (ICP) on the epitaxial film layer of the LED to directly form a micron-scale Micro-LED epitaxial film structure. The fixed spacing of this structure is required for display pixels Then the LED wafer (including the epitaxial layer and the substrate) is directly bonded to the driving circuit substrate, and finally the substrate is peeled off using a physical or chemical mechanism, leaving only the 4~5 micron Micro-LED epitaxial thin film structure on the driving circuit Display pixels are formed on the substrate.

(3) Thin film transfer, that is, to use physical or chemical mechanisms to peel off the LED substrate, use a temporary substrate to carry the LED epitaxial film layer, and then use inductively coupled plasma ion etching to form a micron-scale Micro-LED epitaxial film structure; or, first Inductively coupled plasma ion etching is used to form a micron-scale Micro-LED epitaxial thin film structure, and then the LED substrate is peeled off using a physical or chemical mechanism, and a temporary substrate is used to carry the LED epitaxial thin film structure. Finally, according to the required display pixel pitch on the driving circuit substrate, the Micro LED epitaxial thin film structure is transferred in batches using a selective transfer fixture, and bonded to the driving circuit substrate to form display pixels.

Contents of the invention

In one aspect, the present invention discloses a micro-LED device, which at least includes a substrate and a plurality of LED elements arranged at intervals on the substrate, and the LED element at least includes epitaxial wafers and transparent conductive layers stacked in sequence, and is characterized in that: The plurality of LED elements share one substrate; the inside of the substrate corresponds to a plurality of through holes through the substrate; the back of the substrate also has a metal back plate, and the metal back plate has a plurality of a protrusion corresponding to the through hole, the protrusion is inserted into the through hole and is electrically connected to the epitaxial wafer; a transparent cover plate is provided on the surface of the LED, and the transparent cover plate includes a transparent upper cover plate, a plurality of Conductive pads, a plurality of metal contacts and a plurality of conductive wires, the conductive pads are located on the lower surface of the transparent upper cover and correspond to the positions of the LED elements, the metal contacts are located on the outer periphery of the lower surface of the transparent upper cover, the The conductive wire is connected to the conductive pad and the metal contact; after the transparent cover and the metal back are connected to the power supply, current is injected into the LED element, so that the LED element emits light of a certain wavelength and emits through the transparent cover.

The epitaxial wafer has a P-I-N structure, at least including an N-type layer, a light-emitting layer and a P-type layer stacked in sequence.

The depth of the through hole is greater than or equal to the thickness of the substrate.

The numbers of the metal contacts, conductive wires, conductive pads, LED elements and protrusions are the same.

The metal backplane has an integral structure, and the plurality of LED elements share one metal backplane.

The metal backplane is composed of a plurality of electrically isolated sub-metal backplanes, and each sub-metal backplane corresponds to an LED element; the metal contacts, conductive wires, conductive pads, LED elements, sub-metal backplanes The number of plates and protrusions is the same.

The structure of the metal back plate is a gold or chromium or platinum or titanium or nickel single layer structure or a multilayer structure formed by any of them.

The structure of the metal contact is a gold or chromium or platinum or titanium or nickel single-layer structure or a multi-layer structure formed by any of them.

The materials of the conductive spacer, the conductive wire and the transparent conductive layer are the same, all being indium tin oxide, zinc oxide or indium zinc oxide.

The material of the transparent upper cover is glass or sapphire.

The width of the LED element is 80-100 microns.

In another aspect, the present invention also provides a method for manufacturing the aforementioned micro-LED device, which specifically includes the following steps:

S1, providing a substrate;

S2. Depositing an epitaxial wafer on the substrate;

S3, plating a transparent conductive layer on the surface of the epitaxial wafer;

S4. Etching from the top of the transparent conductive layer to the bottom of the epitaxial wafer to form a plurality of LED elements arranged at intervals, and each LED element includes an epitaxial layer and a transparent conductive layer stacked in sequence;

S5, thinning the substrate;

S6, using a laser inside the substrate to perform multiple stealth cuts longitudinally inside the substrate on the side close to the LED element, to form modified columns corresponding to the positions of the LED elements;

S7. Using a laser to scribe on the back surface of the substrate corresponding to the modified pillars, forming a through hole penetrating the substrate in the substrate;

S8, performing dry etching on the sidewall of the through hole to make the sidewall of the through hole smooth;

S9. Plating a metal backplate on the back of the substrate;

S10. Provide a transparent cover, the transparent cover includes a transparent upper cover, a plurality of conductive spacers, a plurality of metal contacts and a plurality of conductive wires, the conductive spacer is located on the lower surface of the transparent upper cover and is connected with The position of the LED element is corresponding, the metal contact is located on the outer periphery of the lower surface of the transparent upper cover, and the conductive wire is connected to the conductive pad and the metal contact;

S11. Place the transparent cover on the surface of the LED element, bond the cover and the LED element tightly by annealing and fusion, and inject current into the LED after the transparent cover and the metal back plate are connected to the power supply In the component, the LED component emits light of a certain wavelength and emits it through the transparent cover plate.

Preferably, the etching method in step S4 is plasma etching.

Preferably, in the step S6, a laser is used to perform three stealth cuts longitudinally from the bottom of the LED element to the back of the substrate.

Preferably, the temperature range for the annealing and fusion of the conductive spacer and the transparent conductive layer is 400-600°C.

The invention provides a method for manufacturing micro-LED devices by means of epitaxial-level welding, using plasma to directly etch epitaxial wafers to manufacture micron-scale LED elements, without transferring the LED elements, wherein the substrate does not need to be peeled off, but directly inside the substrate A hole is opened to form a through hole, and the metal back plate as the negative electrode passes through the through hole to directly electrically contact the epitaxial wafer. When making the through holes in the substrate, the combination of vertical multiple stealth cutting and laser scribing is used to make the through holes, which is simple and easy to operate. In the present invention, the metal contact located on the outer periphery of the transparent upper cover is designed as the positive pole, and the positive and negative poles are directly connected to realize point-controlled LED element lighting, thereby eliminating the need for wire bonding and transfer operations on micron-sized small-sized LED elements. In the micro-LED device, each contact corresponds to an LED element and a sub-metal backplane, therefore, it is equivalent to a parallel structure of LED elements, and can individually control the light emission of a single LED element.

Description of drawings

FIG. 1 is a schematic diagram of a side view structure of a micro LED device according to Embodiment 1 of the present invention.

FIG. 2 is a schematic top view structure diagram of a micro LED device according to Embodiment 1 of the present invention.

Fig. 3 is a schematic bottom view of the structure of the transparent cover plate according to Embodiment 1 of the present invention.

FIG. 4 is a schematic bottom view of the structure of the micro LED device according to Embodiment 1 of the present invention.

FIG. 5 is a schematic flow chart of a method for manufacturing a micro LED device according to Embodiment 1 of the present invention.

FIG. 6 is a schematic diagram of a side view structure of a micro LED device according to Embodiment 2 of the present invention.

detailed description

In the following paragraphs the invention is described more specifically by way of example with reference to the accompanying drawings. Advantages and features of the present invention will be apparent from the following description and claims. It should be noted that all the drawings are in a very simplified form and use imprecise scales, and are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.

Example 1

Referring to accompanying drawing 1, the present invention discloses micro-LED device on the one hand, comprise at least a substrate 10, a plurality of LED elements arranged at intervals on the substrate 10, a plurality of LED elements share a substrate 10, and periodically Arranged on the substrate 10 (as shown in Figure 2), the inside of the substrate 10 has a plurality of through holes 12 penetrating the substrate corresponding to the LED elements, and the back of the substrate 10 also has a metal back plate 40, the metal back plate 40 There are a plurality of protrusions 41 corresponding to the through holes 12, the protrusions 41 are inserted into the through holes 12 and electrically connected with the epitaxial wafer 20, and a transparent cover plate 50 is placed on the surface of the LED element. The material of the substrate 10 can be sapphire, silicon carbide, silicon, etc., and can be a patterned substrate, or a flat substrate. In this embodiment, a patterned sapphire substrate is preferred.

Among them, the LED element at least includes an epitaxial wafer 20 and a transparent conductive layer 30 stacked in sequence. The epitaxial wafer 20 has a P-I-N structure, and at least includes an N-type layer, a light-emitting layer, and a P-type layer stacked in sequence. For example, n-GaN/InGaN/p-GaN is a blue epitaxial wafer, and the width of the LED element is 80~100 microns, which is smaller than the size of a conventional white lighting LED, so when it is applied to an LED display, the pixel is higher . The transparent conductive layer 30 plays the role of current spreading, and its material is indium tin oxide or zinc oxide or indium zinc oxide, preferably indium tin oxide (ITO) in this implementation. The depth of the through hole 12 is greater than or equal to the thickness of the substrate 10 of the micro LED device. In this embodiment, the depth of the through hole 12 is preferably equal to the thickness of the substrate 10 of the micro LED device. Correspondingly, the height and diameter of the protrusion 41 are consistent with the depth and diameter of the through hole 12 . The metal backplane 40 has an integral structure, and a plurality of LED elements share one metal backplane 40 . The integrated metal backplane 40 has a relatively simple manufacturing process and can be completed in one step. Its material is metal, such as gold, chromium, platinum, titanium, or nickel, and the structure can be a single layer of one of the aforementioned metals. structure or any multi-layer structure formed by several types, in this embodiment, a gold single-layer structure with better conductivity can be used, or a multi-layer structure formed by stacking gold/chromium/platinum/titanium/nickel. In the present invention, the substrate 10 does not need to be removed, but a hole is opened in the substrate 10 so that the protrusion 41 of the metal back plate 40 is in electrical contact with the epitaxial layer 20 to inject current.

Referring to accompanying drawings 1 , 3 and 4 , the transparent cover 50 is composed of a transparent upper cover 51 , a plurality of conductive pads 52 , metal contacts 53 and conductive wires 54 . Specifically, the size of the upper cover plate 51 is larger than the size of the substrate 10 and has the same shape, for example, a conventionally used circle (see FIG. 4 for details). The transparent upper cover 51 is made of a transparent material, such as glass or sapphire. Glass is preferably used in this embodiment, so that the light emitted by the LED element can penetrate the transparent upper cover 51 to realize the light emission of the micro LED device.

The conductive pads 52 are located on the lower surface of the upper cover plate 51 , and are matched with the LED elements, including positional correspondence and number correspondence, that is, the number of the conductive pads 52 is consistent with the LED elements. The conductive spacer 52 can be made of metal or indium tin oxide, zinc oxide or indium zinc oxide material. In this embodiment, it is preferably indium tin oxide that is the same material as the transparent conductive layer 30. The two can be strengthened by bonding. Adhesion firmness. The size of the conductive spacer 52 can be equal to, smaller than or larger than that of the transparent conductive layer 30, and can be specifically set according to needs. In this embodiment, the size of the two is the same, for example, the width is 80-100 microns, which is convenient for subsequent bonding.

The metal contacts 53 are distributed on the outer periphery of the upper cover plate 51, and each metal contact 53 corresponds to one LED element, so the number of the two is the same, and its material is metal, such as gold or chromium or platinum or titanium or nickel, and the structure can be The single-layer structure formed by the aforementioned metal or the multi-layer structure formed by any several kinds can be used in this embodiment. into a multi-layer structure. Each metal contact 53 and a protrusion 41 in the metal back plate 40 form the positive and negative poles of the LED element, and inject current into the LED element to make it emit light.

In order to make the metal contact 53 electrically connected with the conductive spacer 52, a conductive wire 54 is used to connect the two. The material of the conductive wire 54 can be metal, or indium tin oxide or zinc oxide or indium zinc oxide. Since the conductive wire 54 is also fused with the transparent conductive layer 30 when the subsequent conductive spacer 52 is bonded to the transparent conductive layer 30 , the material of the conductive wire 54 is preferably indium tin oxide in this embodiment. In order to apply the LED element to the display, in the present invention, the metal back plate 40 is designed on the back side of the LED element as the negative pole, and the metal contact 53 is designed on its front side as the positive pole. When the metal back plate 40 and the metal contact 53 are connected to the external power supply After being switched on, current is injected into the LED element to make it emit light of a certain wavelength for use by the display.

Referring to accompanying drawing 5, in order to manufacture above-mentioned micro-LED device, the present invention provides its manufacturing method, specifically comprises the following steps:

S1, providing a substrate 10;

S2, depositing an epitaxial wafer 20 on the substrate 10;

S3, plating a transparent conductive layer 30 on the surface of the epitaxial wafer 20;

S4. Etching from the top of the transparent conductive layer 30 to the bottom of the epitaxial wafer 20 to form a plurality of LED elements arranged at intervals; the LED element includes the epitaxial layer 20 and the transparent conductive layer 30 stacked in sequence; the etching method adopts plasma etching;

S5, thinning the substrate 10;

S6. Using a laser inside the substrate 10 to carry out multiple stealth cuts vertically inside the substrate 10 on the side close to the LED element, specifically from the bottom of the LED element to the back of the substrate 10 longitudinally for 3 invisible cuts to form an LED element. The modified column 11 corresponding to the position; the modified column 11 is sapphire whose material properties have been changed. hole 12;

S7. Using a laser to scribe on the back surface of the substrate 10 corresponding to the position of the modified column 11, forming a through hole 12 penetrating the substrate in the substrate 10; the material of the modified column 11 is released from the through hole 12;

S8 , performing dry etching on the sidewall of the through hole 12 to make the sidewall of the through hole 12 smooth. The smooth sidewall of the through hole 12 is more convenient for the subsequent manufacturing process of the metal backplane 40;

S9. Plating a metal backplane 40 on the back of the substrate; the metal backplane 40 can be made by sputtering, vapor deposition or chemical coating;

S10, provide a transparent cover 50, the transparent cover 50 includes a transparent upper cover 51, a plurality of conductive pads 52, a plurality of metal contacts 53 and a plurality of conductive wires 54, the conductive pads 42 are located on the transparent upper cover 51 The lower surface corresponds to the position of the LED element, the metal contact 53 is located on the outer periphery of the lower surface of the transparent upper cover 51, and the conductive wire 54 connects the conductive pad 52 and the metal contact 53;

S11. Place the transparent cover plate 50 on the surface of the LED element, and after bonding, anneal and fuse the transparent cover plate 50 and the LED element to be closely combined. After the transparent cover plate 50 and the metal back plate 40 are connected to the power supply, inject current into the LED element In order to make the LED element emit light of a certain wavelength and emit it through the transparent cover plate 50, the annealing temperature is preferably 400-600°C.

The present invention provides a method for manufacturing micro-LED devices by means of epitaxial welding, which uses plasma to directly etch epitaxial wafers to manufacture micron-scale LED elements without transferring the LED elements. 10 is opened to form a through hole 12, and the metal back plate 40 as the negative electrode passes through the through hole 12 to directly electrically contact the epitaxial wafer 20. When making the through hole 12 in the substrate 10 , the method of combining vertical multiple stealth cutting and laser scribing is used to make the through hole 12 , which is simple and easy to operate. In the present invention, the metal contact 53 located on the outer periphery of the transparent upper cover 51 is designed as the positive pole, and the positive and negative poles are directly connected, so that the LED element can emit light, so that there is no need for wire bonding operation on the micron-sized small-sized LED element.

Example 2

Referring to FIG. 6 , in this embodiment, in order to improve the heat dissipation effect of the micro LED device, the metal backplane 40 can be configured to be composed of a plurality of electrically isolated sub-metal backplanes 42 . Each sub-metal backplane 42 corresponds to each LED element, conductive spacer 52 , metal contact 53 , and conductive wire 54 , with the same number.

In the micro-LED device, each metal contact 53 corresponds to an LED element and a sub-metal backplane 42, therefore, equivalent to a parallel structure of LED elements, the light emission of a single LED element can be individually controlled.

It should be understood that the above specific implementation is a preferred embodiment of the present invention, the scope of the present invention is not limited to this embodiment, and any changes made according to the present invention are within the protection scope of the present invention.

Claims (16)

1. micro- LED component, including at least a substrate, it is spaced in a plurality of LED elements on substrate, the LED element is extremely Few epitaxial wafer and transparency conducting layer for including stacking gradually, it is characterised in that：

A plurality of LED elements share a substrate；

The substrate interior has a plurality of through holes through substrate with LED element correspondence position；

The back side of the substrate also has metal backing, and the metal backing has a plurality of projections corresponding with through hole, described Electrically conducted in projection insertion through hole and with epitaxial wafer；

The LED surface is also equipped with a transparent cover plate, and the transparent cover plate includes transparent upper cover plate, plural conductive cushion block, answered Several hard contacts and plural conductive line, the conductive cushion block be located at transparent upper cover plate lower surface and with LED element position pair Should, the hard contact is located at the periphery of transparent upper cover plate lower surface, the conductor wire connection conductive cushion block and hard contact；

After transparent cover plate and metal backing the access power supply, inject a current into LED element, LED element is launched a standing wave Long light is simultaneously launched through transparent cover plate.

2. micro- LED component according to claim 1, it is characterised in that：The epitaxial wafer is P-I-N structures, is comprised at least N-type layer, luminescent layer and the P-type layer stacked gradually.

3. micro- LED component according to claim 1, it is characterised in that：The depth of the through hole is more than or equal to the lining The thickness at bottom.

4. micro- LED component according to claim 1, it is characterised in that：The hard contact, conductor wire, conductive cushion block, LED element, raised number are identical.

5. micro- LED component according to claim 1, it is characterised in that：The metal backing is structure as a whole, the plural number Individual LED element shares a metal backing.

6. micro- LED component according to claim 1, it is characterised in that：The metal backing is electrically isolated by a plurality of Sub- metal backing composition, each sub- metal backing are corresponding with a LED element.

7. micro- LED component according to claim 6, it is characterised in that：The hard contact, conductor wire, conductive cushion block, LED element, sub- metal backing, raised number are identical.

8. micro- LED component according to claim 1, it is characterised in that：The metal backing for gold or chromium or platinum or titanium or Nickel single layer structure or the sandwich construction of any several formation.

9. micro- LED component according to claim 1, it is characterised in that：The hard contact for gold or chromium or platinum or titanium or Nickel single layer structure or the sandwich construction of any several formation.

10. micro- LED component according to claim 1, it is characterised in that：The conductive cushion block, conductor wire, transparency conducting layer Material is identical, is tin indium oxide either zinc oxide or indium-zinc oxide.

A kind of 11. micro- LED component according to claim 1, it is characterised in that：The material of the transparent upper cover plate is glass Or sapphire.

A kind of 12. micro- LED component according to claim 1, it is characterised in that：The width of the LED element is 80 ~ 100 Micron.

13. the preparation method of micro- LED component, specific method step is as follows：

S1, provide a substrate；

S2, in depositing epitaxial wafer on the substrate；

S3, in the epitaxial wafer surface it is coated with transparency conducting layer；

S4, by the top etch of the transparency conducting layer to epitaxial wafer bottom, form a plurality of spaced LED elements, often One LED element includes the epitaxial layer and transparency conducting layer stacked gradually；

S5, the substrate is thinned；

S6, in the substrate interior stealthy cutting is longitudinally carried out repeatedly in the substrate interior close to LED element side using laser, Form the modification post with LED element position correspondence；

S7, scribing carried out on the substrate back surface and modification post correspondence position using laser, formed and passed through in the substrate Wear the through hole of substrate；

S8, the side wall to the through hole carry out dry etching, make the smooth-sided of through hole；

S9, in the substrate back it is coated with metal backing；

S10, a transparent cover plate is provided, the transparent cover plate includes transparent upper cover plate, plural conductive cushion block, a plurality of metals and touched Point and plural conductive line, the conductive cushion block be located at transparent upper cover plate lower surface and with LED element position correspondence, the metal Contact is located at the periphery of transparent upper cover plate lower surface, the conductor wire connection conductive cushion block and hard contact；

S11, the transparent cover plate is placed in LED element surface, the cover plate and LED element are made by fusion of annealing after bonding Electrically combine, after transparent cover plate and metal backing the access power supply, inject a current into LED element, LED element is launched one The light of standing wave length is simultaneously launched through transparent cover plate.

14. the preparation method of micro- LED component according to claim 13, it is characterised in that：Etching in the step S4 Method is plasma etching.

15. the preparation method of micro- LED component according to claim 13, it is characterised in that：Laser is used in substrate interior 3 stealthy cuttings are longitudinally carried out from the bottom of LED element to substrate back, form the modification post with LED element position correspondence.

16. the preparation method of micro- LED component according to claim 13, it is characterised in that：Led described in the step S11 Electrical pad block and the temperature range of transparency conducting layer annealing fusion are 400 ~ 600 DEG C.