Patent Description:
In the recent years, LEDs have become popular in lighting applications. As light sources, LEDs have many advantages including higher light efficiency, lower energy consumption, longer lifetime, smaller size, and faster switching.

Displays having micro-scale LEDs are known as micro-LED. Micro-LED displays have arrays of micro-LEDs forming the individual pixel elements. A pixel may be a minute area of illumination on a display screen, one of many from which an image is composed. In other words, pixels may be small discrete elements that together constitute an image as on a display. Pixels are normally arranged in a two-dimensional (2D) matrix, and are represented using dots, squares, rectangles, or other shapes. Pixels may be the basic building blocks of a display or digital image and with geometric coordinates.

When forming a full color image, a pixel might be composed of multiple sub-pixels emitting light of different colors, and each sub-pixel might be controlled or driven to emit light of different colors. When manufacturing the full color LED display, the sub-pixels emitting light of different colors are fabricated separately because the manufacturing processes or materials of LEDs having different colors are different as well. The sub-pixels are then integrated to form the full color pixel. However, the integration of multiple sub-pixel LEDs to form the full color pixel is difficult in the manufacturing process, and the problem is even more significant when the micro-LED mesas become even smaller. The integration of multiple micro-LEDs on the same platform via mass transfer method is nearly impossible for high resolution micro-display.

Embodiments of the disclosure address the above problems by providing a full color LED structure and the method for manufacturing the same, and therefore multiple sub-pixels emitting different colors can be integrated on the same platform without the drawbacks of mass transfer.

Patent application document No. <CIT> discloses lighting systems, the lighting systems include an electrically insulating carrier having a plurality of conductive elements disposed thereon, a light-emitting array, and at least one power source. The light-emitting array is disposed over the carrier and includes a plurality of light-emitting strings, each light-emitting string comprising a plurality of unpackaged light-emitting diode (LED) dies electrically connected in series. Each LED die has at least two electrical contacts on one surface thereof, and each electrical contact is electrically connected to a conductive element by a conductive adhesive. The power source provides power to the light-emitting strings.

Patent application document No. <CIT> discloses a color mixing light emitting diode (LED). The present invention is featured in that a plurality of LEDs emitting different colors of light can be electrically connected in series and/or in parallel by using chip manufacturing to generate other colors of light. For example, the first LED chip set can emit such as yellow light (or changing to reddish-red light), and the second LED chip can emit such as blue light (or changing to bluish-green light), thereby making the present invention to emit white light. Moreover, the first LED chip set can be a photoluminescence LED chip, wherein the first LED chip can be excited by the light emitted by the second LED chip to emit light, and then the light emitted by the second LED chip and the light emitted by the first LED chip can be mixed into other colors of light.

Patent application document No. <CIT> discloses a light-emitting diode (LED) chip and a display device having the same are provided. A green LED is regrown on a blue LED to produce blue and green light, and a red phosphor is disposed on the blue or green LED to produce red light. Red light, green light, and blue light are to be produced using a single LED chip. The single LED chip forms three subpixels therein so as to facilitate a transfer process of the LED chip to a display panel. The LED chip is configured based on the blue, green, and blue LEDs so as to facilitate the fabrication and driving of the LED chip.

Patent application document No. <CIT> discloses an improved method of creating LED arrays is disclosed. A p-type layer, multi-quantum well and n-type layer are disposed on a substrate. The device is then etched to expose portions of the n-type layer. To create the necessary electrical isolation between adjacent LEDs, an ion implantation is performed to create a non-conductive implanted region. In some embodiments, an implanted region extends through the p-type layer, MQW and n-type layer. In another embodiment, a first implanted region is created in the n-type layer. In addition, a second implanted region is created in the p-type layer and multi-quantum well immediately adjacent to etched n-type layer. In some embodiments, the ion implantation is done perpendicular to the substrate. In other embodiments, the implant is performed at an angle.

Embodiments of the LED structure and method for forming the LED structure are disclosed herein.

An LED structure is disclosed. The LED structure includes a substrate and a plurality of LED units formed on the substrate. Each LED unit includes a first doping semiconductor layer, a multiple quantum well (MQW) layer formed on the first doping semiconductor layer, and a second doping semiconductor layer formed on the MQW layer. The plurality of LED units include a first LED unit and a second LED unit formed on the substrate and horizontally adjacent to each other. The second doping semiconductor layer of the first LED unit is electrically isolated with the second doping semiconductor layer of the second LED unit by an ion-implanted material formed above the first doping semiconductor layer and the MQW layer. The plurality of LED units further includes a third LED unit formed above the ion-implanted material, the first LED unit and the second LED unit emit light of a first color, the third LED unit emits light of a second color different from the first color, a color conversion layer formed on the first LED unit to convert light of the first color to light of a third color different from the first color and the second color.

In a further example, a method for manufacturing a LED structure is disclosed. A first semiconductor layer is formed on a first substrate. The first semiconductor layer includes a first doping semiconductor layer, a first multiple quantum well (MQW) layer on the first doping semiconductor layer, and a second doping semiconductor layer on the first MQW layer. A first implantation operation is performed to form a first implanted region and a first non-implanted region in the second doping semiconductor layer. A second semiconductor layer is formed on the first semiconductor layer. The second semiconductor layer includes a third doping semiconductor layer, a second MQW layer on the third doping semiconductor layer, and a fourth doping semiconductor layer on the second MQW layer. A second implantation operation is performed to form a second implanted region and a second non-implanted region in the fourth doping semiconductor layer. A first etch operation is performed to remove a portion of the second semiconductor layer and expose at least the first non-implanted region in the second doping semiconductor layer. A second etch operation is performed to expose a plurality of contacts of a driving circuit formed in the first substrate. The first non-implanted region in the second doping semiconductor layer and the second non-implanted region in the fourth doping semiconductor layer are electrically connected with the plurality of contacts, the first LED unit and the second LED unit emit light of a first color, the third LED unit emits light of a second color different from the first color, a color conversion layer formed on the first LED unit to convert light of the first color to light of a third color different from the first color and the second color.

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate implementations of the present disclosure and, together with the description, further serve to explain the present disclosure and to enable a person skilled in the pertinent art to make and use the present disclosure.

Implementations of the present disclosure will be described with reference to the accompanying drawings.

Although specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. As such, other configurations and arrangements can be used without departing from the scope of the present disclosure. Also, the present disclosure can also be employed in a variety of other applications. Functional and structural features as described in the present disclosures can be combined, adjusted, and modified with one another and in ways not specifically depicted in the drawings, such that these combinations, adjustments, and modifications are within the scope of the present discloses.

A substrate can be a layer, can include one or more layers therein, and/or can have one or more layers thereupon, thereabove, and/or therebelow. For example, a semiconductor layer can include one or more doped or undoped semiconductor layers and may have the same or different materials.

Furthermore, the substrate can include a wide array of semiconductor materials, such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, indium phosphide, etc. Alternatively, the substrate can be made from an electrically non-conductive material, such as a glass, a plastic, or a sapphire wafer. Further alternatively, the substrate can have semiconductor devices or circuits formed therein.

As used herein, the term "micro" LED, "micro" p-n diode or "micro" device refers to the descriptive size of certain devices or structures according to implementations of the invention. As used herein, the terms "micro" devices or structures are meant to refer to the scale of <NUM> to <NUM>. However, it is to be appreciated that implementations of the present invention are not necessarily so limited, and that certain aspects of the implementations may be applicable to larger, and possibly smaller size scales.

Implementations of the present disclosure describe a full color LED structure or a full color micro-LED structure and a method for manufacturing the structure. For manufacturing a full color micro-LED display, multiple sub-pixels with different emitting colors, e.g., red, green, and blue, are integrally formed and become a full color pixel. The sub-pixel micro-LEDs are individually driven by one or more driving circuits to separately emit primary colors with corresponding color scales, and the human eyes can see a full range of colors of the full color pixel composed of multiple sub-pixels.

To integrally form the multiple sub-pixel LEDs or micro-LEDs emitting different colors, e.g., three primary colors, on the same substrate, a stacking structure of LED units is disclosed, and the LED units include a substantially flat top surface to achieve the stacking structure. The two layers of LED unit emits two different colors. Furthermore, a color conversion layer is deposited on one of the LED unit in the first layer to convert the emitting color of the LED unit to a third different color.

<FIG> illustrates a top view of an exemplary LED structure <NUM>, not forming part of the invention as claimed. <FIG> illustrates a cross section of LED structure <NUM> along line A-A', and <FIG> illustrates a cross section of LED structure <NUM> along line B-B', not forming part of the invention as claimed. For the purpose of better explaining the present disclosure, the top view of LED structure <NUM> in <FIG> and the cross sections of LED structure <NUM> in <FIG> will be described together.

As shown in <FIG> and <FIG>, LED structure <NUM> includes a first substrate <NUM>, a first semiconductor layer <NUM> formed on first substrate <NUM>, and a second semiconductor layer <NUM> formed on first semiconductor layer <NUM>. First semiconductor layer <NUM> includes a first LED unit <NUM> and a second LED unit <NUM>, and second semiconductor layer <NUM> includes a third LED unit <NUM>. First LED unit <NUM> and second LED unit <NUM> are at the same horizontal level and are horizontally adjacent to each other. Third LED unit <NUM> is formed in second semiconductor layer <NUM> above first LED unit <NUM> and second LED unit <NUM>.

First substrate <NUM> may include a semiconductor material, such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, or indium phosphide. In some implementations, first substrate <NUM> may be made from an electrically non-conductive material, such as a glass, a plastic or a sapphire wafer. In some implementations, first substrate <NUM> may have driving circuits formed therein, and first substrate <NUM> may be CMOS backplane or TFT glass substrate. The driving circuit provides the electronic signals to LED structure <NUM> to control the luminance. In some implementations, the driving circuit may include an active matrix driving circuit, in which each individual LED unit corresponds to an independent driver. In some implementations, the driving circuit may include a passive matrix driving circuit, in which the LED units are aligned in an array and are connected to the data lines and the scan lines driven by the driving circuit.

First semiconductor layer <NUM> includes a first doping semiconductor layer <NUM>, a first multiple quantum well (MQW) layer <NUM> formed on first doping semiconductor layer <NUM>, and a second doping semiconductor layer <NUM> formed on first MQW layer <NUM>. In some implementations, first doping semiconductor layer <NUM> and second doping semiconductor layer <NUM> may include one or more layers formed with II-VI materials, such as ZnSe or ZnO, or III-V nitride materials, such as GaN, AlN, InN, InGaN, GaP, AlInGaP, AlGaAs, and their alloys. In some implementations, first doping semiconductor layer <NUM> may be a p-type semiconductor layer that extends across first LED unit <NUM> and second LED unit <NUM> and forms a common anode of first LED unit <NUM> and second LED unit <NUM>. In some implementations, first doping semiconductor layer <NUM> may include p-type GaN. In some implementations, first doping semiconductor layer <NUM> may be formed by doping magnesium (Mg) in GaN. In some implementations, first doping semiconductor layer <NUM> may include p-type InGaN. In some implementations, first doping semiconductor layer <NUM> may include p-type AlInGaP.

By having a thin layer of continuous first doping semiconductor layer <NUM> across multiple LED units, e.g., first LED unit <NUM> and second LED unit <NUM>, the bonding area between first substrate <NUM> and the plurality of LED units is extended. Hence, the bonding strength between first substrate <NUM> and the plurality of LED units is increased and the risk of peeling-off of LED structure <NUM> can be reduced.

In some implementations, second doping semiconductor layer <NUM> may be a n-type semiconductor layer and form a cathode of first LED unit <NUM> and second LED unit <NUM>. In some implementations, second doping semiconductor layer <NUM> may include n-type GaN. In some implementations, second doping semiconductor layer <NUM> may include n-type InGaN. In some implementations, second doping semiconductor layer <NUM> may include n-type AlInGaP. Second doping semiconductor layer <NUM> of different LED units, e.g., first LED unit <NUM> and second LED unit <NUM>, are electrically isolated, thus each LED unit having a cathode that can have a voltage level different from the other units. First LED unit <NUM> and second LED unit <NUM> further include first MQW layer <NUM> formed between first doping semiconductor layer <NUM> and second doping semiconductor layer <NUM>. First MQW layer <NUM> is the active region of first LED unit <NUM> and second LED unit <NUM>.

As a result of the disclosed implementations, first LED unit <NUM> and second LED unit <NUM> are formed with their first doping semiconductor layer <NUM> horizontally extended across the adjacent LED units, and their second doping semiconductor layers <NUM> electrically isolated between the adjacent LED units. Second doping semiconductor layers <NUM> of first LED unit <NUM> and second LED unit <NUM> are isolated by implanted regions in a first ion-implanted material <NUM>. Non-implanted regions of first ion-implanted material <NUM> may also define the light emitting area of first LED unit <NUM> and second LED unit <NUM>. In some implementations, first ion-implanted material <NUM> may be formed by implanting ion materials in second doping semiconductor layers <NUM>. In some implementations, first ion-implanted material <NUM> may be formed by implanting H+, He+, N+, O+, F+, Mg+, Si+ or Ar+ ions in second doping semiconductor layers <NUM>. In some implementations, second doping semiconductor layers <NUM> may be implanted with one or more ion materials to form first ion-implanted material <NUM>. First ion-implanted material <NUM> has the physical properties of electrical insulation. By implanting an ion material in a defined area of second doping semiconductor layer <NUM>, the material of second doping semiconductor layers <NUM> in the defined area may be transformed to first ion-implanted material <NUM>, which electrically isolates second doping semiconductor layers <NUM> of first LED unit <NUM> and second LED unit <NUM> from each other.

In some implementations, the implantation depth of first ion-implanted material <NUM> may be controlled to stop above first MQW layer <NUM>, as shown in <FIG>. In some implementations, the implantation depth of first ion-implanted material <NUM> may be controlled to not penetrate first MQW layer <NUM> and first ion-implanted material <NUM> stops short to contact first doping semiconductor layer <NUM>. It is understood that the location, shape, and depth of first ion-implanted material <NUM> shown in <FIG> are merely illustrative and are not limiting, and those skilled in the art can change according to requirements.

First semiconductor layer <NUM> may be bonded to first substrate <NUM> through a first bonding layer <NUM>, as shown in <FIG>. First bonding layer <NUM> is a layer of an adhesive material formed on first substrate <NUM> to bond first substrate <NUM> and first semiconductor layer <NUM>. In some implementations, first bonding layer <NUM> may include a conductive material, such as metal or metal alloy. In some implementations, first bonding layer <NUM> may include Au, Sn, In, Cu or Ti. In some implementations, first bonding layer <NUM> may include a non-conductive material, such as polyimide (PI), polydimethylsiloxane (PDMS). In some implementations, first bonding layer <NUM> may include a photoresist, such as SU-<NUM> photoresist. In some implementations, first bonding layer <NUM> may be hydrogen silsesquioxane (HSQ) or divinylsiloxane-bis-benzocyclobutene (DVS-BCB). It is understood that the descriptions of the material of first bonding layer <NUM> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

LED structure <NUM> may further include a first reflective layer <NUM> formed between first semiconductor layer <NUM> and first bonding layer <NUM>. First reflective layer <NUM> is formed on first bonding layer <NUM>. In some implementations, first reflective layer <NUM> may include a reflective p-type Ohmic contact layer. First reflective layer <NUM> may provide a current conduction from first LED unit <NUM> and second LED unit <NUM> to first bonding layer <NUM>. First reflective layer <NUM> may also function as a metal mirror to reflect the light emitted by first LED unit <NUM> and second LED unit <NUM>. In some implementations, first reflective layer <NUM> may be a metal or metal alloy layer having a high reflectivity, e.g., silver, aluminum, gold, and their alloys. It is understood that the descriptions of the material of first reflective layer <NUM> are merely illustrative and are not limiting, and other materials are also contemplated.

Second semiconductor layer <NUM> is formed above first semiconductor layer <NUM>. Second semiconductor layer <NUM> includes a third doping semiconductor layer <NUM>, a second MQW layer <NUM> formed on third doping semiconductor layer <NUM>, and a fourth doping semiconductor layer <NUM> formed on second MQW layer <NUM>.

In some implementations, third doping semiconductor layer <NUM> and fourth doping semiconductor layer <NUM> may include one or more layers formed with II-VI materials, such as ZnSe or ZnO, or III-V nitride materials, such as GaN, AlN, InN, InGaN, GaP, AlInGaP, AlGaAs, and their alloys. In some implementations, third doping semiconductor layer <NUM> may be a p-type semiconductor layer. In some implementations, third doping semiconductor layer <NUM> may include p-type GaN. In some implementations, third doping semiconductor layer <NUM> may be formed by doping magnesium (Mg) in GaN. In some implementations, third doping semiconductor layer <NUM> may include p-type InGaN. In some implementations, third doping semiconductor layer <NUM> may include p-type AlInGaP.

In some implementations, fourth doping semiconductor layer <NUM> may be a n-type semiconductor layer and form a cathode of third LED unit <NUM>. In some implementations, fourth doping semiconductor layer <NUM> may include n-type GaN. In some implementations, fourth doping semiconductor layer <NUM> may include n-type InGaN. In some implementations, fourth doping semiconductor layer <NUM> may include n-type AlInGaP. Third LED unit <NUM> further includes second MQW layer <NUM> formed between third doping semiconductor layer <NUM> and fourth doping semiconductor layer <NUM>. Second MQW layer <NUM> is the active region of third LED unit <NUM>.

A second ion-implanted material <NUM> may be formed in fourth doping semiconductor layers <NUM> of third LED unit <NUM> to define the light emitting area of third LED unit <NUM>. In some implementations, second ion-implanted material <NUM> may be formed by implanting ion materials in fourth doping semiconductor layers <NUM>. In some implementations, second ion-implanted material <NUM> may be formed by implanting H+, He+, N+, O+, F+, Mg+, Si+ or Ar+ ions in fourth doping semiconductor layers <NUM>. In some implementations, fourth doping semiconductor layers <NUM> may be implanted with one or more ion materials to form second ion-implanted material <NUM>. Second ion-implanted material <NUM> has the physical properties of electrical insulation. By implanting ion material in a defined area of fourth doping semiconductor layer <NUM>, the material of fourth doping semiconductor layers <NUM> in the defined area may be transformed to second ion-implanted material <NUM>.

In some implementations, the implantation depth of second ion-implanted material <NUM> may be controlled above second MQW layer <NUM>, as shown in <FIG>. In some implementations, the implantation depth of second ion-implanted material <NUM> may be controlled to not penetrate second MQW layer <NUM> and second ion-implanted material <NUM> stops short to contact third doping semiconductor layer <NUM>. It is understood that the location, shape, and depth of second ion-implanted material <NUM> shown in <FIG> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

Second semiconductor layer <NUM> may be bonded to first semiconductor layer <NUM> through a second bonding layer <NUM>, as shown in <FIG>. Second bonding layer <NUM> is a layer of an adhesive material formed on first semiconductor layer <NUM> to bond second semiconductor layer <NUM> and first semiconductor layer <NUM>. In some implementations, second bonding layer <NUM> may include a conductive material, such as metal or metal alloy. In some implementations, second bonding layer <NUM> may include Au, Sn, In, Cu or Ti. In some implementations, second bonding layer <NUM> may include a non-conductive material, such as polyimide (PI), polydimethylsiloxane (PDMS). In some implementations, second bonding layer <NUM> may include a photoresist, such as SU-<NUM> photoresist. In some implementations, second bonding layer <NUM> may be hydrogen silsesquioxane (HSQ) or divinylsiloxane-bis-benzocyclobutene (DVS-BCB). It is understood that the descriptions of the material of first bonding layer <NUM> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

LED structure <NUM> may further include a second reflective layer <NUM> formed between second semiconductor layer <NUM> and second bonding layer <NUM>. Second reflective layer <NUM> is formed on second bonding layer <NUM>. In some implementations, second reflective layer <NUM> may include a reflective p-type Ohmic contact layer. Second reflective layer <NUM> may provide a current conduction from third LED unit <NUM> to second bonding layer <NUM>. Second reflective layer <NUM> may also function as a metal mirror to reflect the light emitted by third LED unit <NUM>. In some implementations, second reflective layer <NUM> may be a metal or metal alloy layer having a high reflectivity, e.g., silver, aluminum, gold, and their alloys. It is understood that the descriptions of the material of second reflective layer <NUM> are merely illustrative and are not limiting, and other materials are also contemplated.

As shown in <FIG>, a portion of second semiconductor layer <NUM> is removed to expose the light emitting area (second doping semiconductor layer <NUM>) of first LED unit <NUM> and second LED unit <NUM>. Furthermore, another portion of first semiconductor layer <NUM> and second semiconductor layer <NUM> is removed to expose the contacts <NUM> of the driving circuit. A passivation layer <NUM> is formed covering first semiconductor layer <NUM> and second semiconductor layer <NUM> and expose second doping semiconductor layer <NUM>, fourth doping semiconductor layer <NUM>, and contacts <NUM>. In some implementations, passivation layer <NUM> may include SiO2, Al2O3, SiN or other suitable materials. In some implementations, passivation layer <NUM> may include polyimide, SU-<NUM> photoresist, or other photo-patternable polymer. An electrode layer is formed to electrically connect second doping semiconductor layer <NUM> with contact <NUM>, and fourth doping semiconductor layer <NUM> with contact <NUM>. In some implementations, electrode layer <NUM> may be conductive materials, such as indium tin oxide (ITO), Cr, Ti, Pt, Au, Al, Cu, Ge or Ni.

By using first ion-implanted material <NUM> to isolate first LED unit <NUM> and second LED unit <NUM> and define the light emitting area of first LED unit <NUM> and second LED unit <NUM>, the top surface of the light emitting area (second doping semiconductor layer <NUM>) and the non-light emitting area (first ion-implanted material <NUM>) can be formed coplanar, and the top surface of first semiconductor layer <NUM> may be kept substantially flat as well. Hence second semiconductor layer <NUM> could be formed or bonded on first semiconductor layer <NUM>.

By using different materials to form first semiconductor layer <NUM> and second semiconductor layer <NUM>, first LED unit <NUM> and second LED unit <NUM> can be manufactured to emit light of a first color, and third LED unit <NUM> can be manufactured to emit light of a second color. For example, by using InGaN or doping magnesium (Mg) in GaN to form first semiconductor layer <NUM>, first LED unit <NUM> and second LED unit <NUM> may emit blue light. For another example, by using InGaN with higher indium composition to form second semiconductor layer <NUM>, third LED unit <NUM> may emit green light.

Implementations of the present disclosure include the stacking structure of first semiconductor layer <NUM> and second semiconductor layer <NUM>, and first semiconductor layer <NUM> and second semiconductor layer <NUM> may be formed by different materials to manufacture LED units emitting light of different colors. Hence, LED structure <NUM> can achieve light emission of different colors by multiple LED units while avoiding the drawbacks of mass transfer.

<FIG> illustrates a top view of another exemplary LED structure <NUM>, according to the invention. <FIG> illustrates a cross section of LED structure <NUM> along line A-A', and <FIG> illustrates a cross section of LED structure <NUM> along line B-B', according to the invention. For the purpose of better explaining the present disclosure, the top view of LED structure <NUM> in <FIG> and the cross sections of LED structure <NUM> in <FIG> will be described together.

LED structure <NUM> is similar to LED structure <NUM> and also includes first substrate <NUM>, first semiconductor layer <NUM> formed on first substrate <NUM>, and second semiconductor layer <NUM> formed on first semiconductor layer <NUM>. First semiconductor layer <NUM> includes first LED unit <NUM> and second LED unit <NUM>, and second semiconductor layer <NUM> includes third LED unit <NUM>. First LED unit <NUM> and second LED unit <NUM> are horizontally adjacent to each other. Third LED unit <NUM> is formed in second semiconductor layer <NUM> above first LED unit <NUM> and second LED unit <NUM>.

As described above, the top surface of first semiconductor layer <NUM> may be substantially flat, and second semiconductor layer <NUM> could be formed or bonded on first semiconductor layer <NUM>. Furthermore, by using different materials to form first semiconductor layer <NUM> and second semiconductor layer <NUM>, first LED unit <NUM> and second LED unit <NUM> may emit light of the first color, and third LED unit <NUM> may emit light of the second color. As shown in <FIG> and <FIG>, a color conversion layer <NUM> is formed on first LED unit <NUM>. Color conversion layer <NUM> may convert light of the first color to a third color. In some implementations, color conversion layer <NUM> may include phosphor. For example, color conversion layer <NUM> may include Cerium (III)-doped YAG (YAG:Ce3+, or Y3Al5O12:Ce3+) to absorb blue light and emit red light. In some implementations, color conversion layer <NUM> may include quantum dots. For example, the quantum dots formed on first LED unit <NUM> may convert blue light and to red light. In some implementations, by using different color quantum dots, light of first LED unit <NUM> may be converted to other colors.

In some implementations, color conversion layer <NUM> may be formed on first LED unit <NUM> by printing technology. In some implementations, color conversion layer <NUM> may be formed on first LED unit <NUM> by the photolithography process. It is understood that the descriptions of the material and the manufacture method of color conversion layer <NUM> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

By forming color conversion layer <NUM> on first LED unit <NUM> to convert the first color emitted by first LED unit <NUM> to the third color, LED structure <NUM> emits at least three different colors. When individually applying different bias voltages to first LED unit <NUM>, second LED unit <NUM>, and third LED unit <NUM> (three sub-pixels), the three primary colors, e.g., red, green and blue, may integrally form a full color pixel.

<FIG> illustrate cross sections of an exemplary LED structure <NUM> at different stages of a manufacturing process, according to the invention. <FIG> illustrate top views of LED structure <NUM> at different stages of a manufacturing process, according to the invention. <FIG> is a flowchart of an exemplary method <NUM> for manufacturing LED structure <NUM>, according to the invention. For the purpose of better describing the present disclosure, the cross sections of LED structure <NUM> in <FIG>, the top views of LED structure <NUM> in <FIG>, and the flowchart of method <NUM> in <FIG>, will be described together.

As shown in <FIG>, a driving circuit is formed in first substrate <NUM> and the driving circuit includes a plurality of contacts <NUM>. For example, the driving circuit may include CMOS devices manufactured on a silicon wafer and some wafer-level packaging layers or fan-out structures are stacked on the CMOS devices to form contacts <NUM>. For another example, the driving circuit may include TFTs manufactured on a glass substrate and some wafer-level packaging layers or fan-out structures are stacked on the TFTs to form contacts <NUM>. First semiconductor layer <NUM> is formed on a second substrate <NUM>, and first semiconductor layer <NUM> includes first doping semiconductor layer <NUM>, second doping semiconductor layer <NUM> and first MQW layer <NUM>.

In some implementations, first substrate <NUM> or second substrate <NUM> may include a semiconductor material, such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, indium phosphide. In some implementations, first substrate <NUM> or second substrate <NUM> may be made from an electrically non-conductive material, such as a glass, a plastic or a sapphire wafer. In some implementations, first substrate <NUM> may have driving circuits formed therein, and first substrate <NUM> may include a CMOS backplane or TFT glass substrate. In some implementations, first doping semiconductor layer <NUM> and second doping semiconductor layer <NUM> may include one or more layers based on II-VI materials, such as ZnSe or ZnO, or III-V nitride materials, such as GaN, AlN, InN, InGaN, GaP, AlInGaP, AlGaAs, and their alloys. In some implementations, first doping semiconductor layer <NUM> may include a p-type semiconductor layer, and second doping semiconductor layer <NUM> may include a n-type semiconductor layer.

In <FIG>, first reflective layer <NUM> is optionally formed on first semiconductor layer <NUM>. In some implementations, first reflective layer <NUM> may include a reflective p-type Ohmic contact layer. First reflective layer <NUM> may also function as a metal mirror to reflect the light emitted by the LED units. In some implementations, first reflective layer <NUM> may be a metal or metal alloy layer having a high reflectivity, e.g., silver, aluminum, gold, and their alloys.

Then, in operation <NUM> of <FIG> and as shown in <FIG>, second substrate <NUM>, first reflective layer <NUM>, and first semiconductor layer <NUM>, including first doping semiconductor layer <NUM>, second doping semiconductor layer <NUM> and first MQW layer <NUM>, are flipped over and bonded to first substrate <NUM> through first bonding layer <NUM>. Then, second substrate <NUM> is removed from first semiconductor layer <NUM>.

In some implementations, first bonding layer <NUM> may include a conductive material, such as metal or metal alloy. In some implementations, first bonding layer <NUM> may include Au, Sn, In, Cu or Ti. In some implementations, first bonding layer <NUM> may include a non-conductive material, such as polyimide (PI), or polydimethylsiloxane (PDMS). In some implementations, first bonding layer <NUM> may include a photoresist, such as SU-<NUM> photoresist. In some implementations, first bonding layer <NUM> may include hydrogen silsesquioxane (HSQ) or divinylsiloxane-bis-benzocyclobutene (DVS-BCB). <FIG> shows a single layer structure of first bonding layer <NUM>, however, in some implementations, first bonding layer <NUM> may include one or multiple layers to bond first substrate <NUM> and first reflective layer <NUM>. For example, first bonding layer <NUM> may include a single conductive or non-conductive layer. For another example, first bonding layer <NUM> may include an adhesive layer and a conductive or non-conductive layer. It is understood that the descriptions of the material of first bonding layer <NUM> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

In operation <NUM> of <FIG>, a first implantation operation is performed to form a first implanted region <NUM> and a first non-implanted region <NUM> in second doping semiconductor layer <NUM>. <FIG> illustrates a top view of LED structure <NUM> after performing the first implantation operation. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>.

Optionally, before performing the first implantation operation, a thinning operation may be performed on second doping semiconductor layer <NUM> to remove a portion of second doping semiconductor layer <NUM> to a predefined thickness. In some implementations, the thinning operation may include a dry etching or a wet etching operation. In some implementations, the thinning operation may include a chemical-mechanical polishing (CMP) operation.

After the first implantation operation, first implanted region <NUM> and first non-implanted region <NUM> are defined in second doping semiconductor layer <NUM>. The material in first non-implanted region <NUM> may be the same as second doping semiconductor layer <NUM>. The material in first implanted region <NUM> may be transformed from second doping semiconductor layer <NUM> to first ion-implanted material <NUM> by the first implantation operation. First implanted region <NUM> (first ion-implanted material <NUM>) isolates LED units <NUM> and <NUM> later formed in first semiconductor layer <NUM>, and first non-implanted region <NUM> (second doping semiconductor layer <NUM>) may define the light emitting region of LED units <NUM> and <NUM> later formed in first semiconductor layer <NUM>.

In some implementations, first ion-implanted material <NUM> may be formed by implanting H+, He+, N+, O+, F+, Mg+, Si+ or Ar+ ions in second doping semiconductor layers <NUM>. In some implementations, second doping semiconductor layers <NUM> may be implanted with one or more ion materials to form first ion-implanted material <NUM>. First ion-implanted material <NUM> has the physical properties of electrical insulation. By implanting ion material in a defined area of second doping semiconductor layers <NUM>, the material of second doping semiconductor layer <NUM> in the defined area may be transformed to first ion-implanted material <NUM> and electrically isolate LED mesas of first LED unit <NUM> and second LED unit <NUM>.

In some implementations, first ion-implanted material <NUM> may be formed in second doping semiconductor layer <NUM> for a depth not sufficient to penetrate first MQW layer <NUM>. In some implementations, the implantation depth of first ion-implanted material <NUM> may be controlled so that first ion-implanted material <NUM> stops short to contact first MQW layer <NUM>, as shown in <FIG>. First MQW layer <NUM>, first doping semiconductor layer <NUM>, first reflective layer <NUM> and bonding layer <NUM> beneath each LED mesa may horizontally extend to first MQW layer <NUM>, first doping semiconductor layer <NUM>, first reflective layer <NUM> and bonding layer <NUM> beneath adjacent LED mesas.

By using first ion-implanted material <NUM> to isolate first LED unit <NUM> and second LED unit <NUM> and define the light emitting area of first LED unit <NUM> and second LED unit <NUM>, the top surface of the light emitting area (second doping semiconductor layer <NUM>) and the non-light emitting area (first ion-implanted material <NUM>) can be formed coplanar, and the top surface of first semiconductor layer <NUM> may be kept substantially flat as well. Hence another semiconductor layer (second semiconductor layer <NUM>) could be later formed or bonded on first semiconductor layer <NUM>.

Referring to operation <NUM> of <FIG> and <FIG>, second semiconductor layer <NUM> is formed on first semiconductor layer <NUM>. Second semiconductor layer <NUM> includes third doping semiconductor layer <NUM>, second MQW layer <NUM> on third doping semiconductor layer <NUM>, and fourth doping semiconductor layer <NUM> on second MQW layer <NUM>. Similar to the manufacturing process of first semiconductor layer <NUM>, second semiconductor layer <NUM> may be first formed on a third substrate (not shown), and second reflective layer <NUM> may be optionally formed on second semiconductor layer <NUM>. Then, the third substrate, second semiconductor layer <NUM>, and second reflective layer <NUM> are flipped over and bonded to first semiconductor layer <NUM> through second bonding layer <NUM>. Then, the third substrate is removed from second semiconductor layer <NUM>.

Referring to operation <NUM> of <FIG>, a second implantation operation is performed to form a second implanted region <NUM> and a second non-implanted region <NUM> in fourth doping semiconductor layer <NUM>. <FIG> illustrates a top view of LED structure <NUM> after performing the second implantation operation. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>.

Optionally, before performing the second implantation operation, a thinning operation may be performed on fourth doping semiconductor layer <NUM> to remove a portion of fourth doping semiconductor layer <NUM> to a predefined thickness. In some implementations, the thinning operation may include a dry etching or a wet etching operation. In some implementations, the thinning operation may include a chemical-mechanical polishing (CMP) operation.

After the second implantation operation, second implanted region <NUM> and second non-implanted region <NUM> are defined in fourth doping semiconductor layer <NUM>. The material in second non-implanted region <NUM> may be the same as fourth doping semiconductor layer <NUM>. The material in second implanted region <NUM> may be transformed from fourth doping semiconductor layer <NUM> to second ion-implanted material <NUM> by the second implantation operation. Second implanted region <NUM> (second ion-implanted material <NUM>) may isolate third LED unit <NUM> later formed in second semiconductor layer <NUM> with other LED units, and second non-implanted region <NUM> (fourth doping semiconductor layer <NUM>) may define the light emitting region of third LED unit <NUM> later formed in second semiconductor layer <NUM>.

In some implementations, second ion-implanted material <NUM> may be formed by implanting H+, He+, N+, O+, F+, Mg+, Si+ or Ar+ ions in fourth doping semiconductor layers <NUM>. In some implementations, fourth doping semiconductor layers <NUM> may be implanted with one or more ion materials to form second ion-implanted material <NUM>. Second ion-implanted material <NUM> has the physical properties of electrical insulation. By implanting ion material in a defined area of fourth doping semiconductor layers <NUM>, the material of fourth doping semiconductor layer <NUM> in the defined area may be transformed to second ion-implanted material <NUM> and electrically isolate LED mesa of third LED unit <NUM> with other LED units.

In some implementations, second ion-implanted material <NUM> may be formed in fourth doping semiconductor layer <NUM> for a depth not sufficient to penetrate second MQW layer <NUM>. In some implementations, the implantation depth of second ion-implanted material <NUM> may be controlled so that second ion-implanted material <NUM> stops short to contact second MQW layer <NUM>, as shown in <FIG>.

In operation <NUM> of <FIG>, a first etch operation is performed to remove a portion of second semiconductor layer <NUM>, a portion of second reflective layer <NUM>, and a portion of second bonding layer, and expose at least first non-implanted region <NUM> in the second doping semiconductor layer <NUM>. <FIG> illustrates a top view of LED structure <NUM> after performing the first etch operation. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>. In some implementations, the first etch operation may be dry etch, wet etch, or other suitable processes.

As shown in <FIG>, two rectangle regions are removed from second semiconductor layer <NUM>, and these two rectangle regions may be the regions of first LED unit <NUM> and second LED unit <NUM>. The exposed regions include second doping semiconductor layer <NUM> and a portion of first ion-implanted material <NUM>. The first etch operation is performed to remove a portion of second semiconductor layer <NUM> above the light emitting areas of first semiconductor layer <NUM>, and also expose a portion of first semiconductor layer <NUM> above the plurality of contacts <NUM> that will be exposed in a later operation. It is understood that the location and shape of exposed second doping semiconductor layer <NUM> and first ion-implanted material <NUM> shown in <FIG> and <FIG> are merely illustrative and are not limiting, and those skilled in the art can make changes according to requirements.

In operation <NUM> of <FIG>, a second etch operation is performed to expose a plurality of contacts <NUM> of the driving circuit formed in first substrate <NUM>. <FIG> illustrates a top view of LED structure <NUM> after performing the second etch operation. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>. Then, as shown in <FIG>, passivation layer <NUM> is formed over first semiconductor layer <NUM> and second semiconductor layer <NUM>, and first non-implanted region <NUM> in second doping semiconductor layer <NUM>, second non-implanted region <NUM> in fourth doping semiconductor layer <NUM>, and the plurality of contacts <NUM> are exposed. In some implementations, passivation layer <NUM> may include SiO2, Al2O3, SiN or other suitable materials for isolation and protection. In some implementations, passivation layer <NUM> may include polyimide, SU-<NUM> photoresist, or other photo-patternable polymer.

In operation <NUM> of <FIG>, first non-implanted region <NUM> in second doping semiconductor layer <NUM> is electrically connected to contact <NUM> through electrode layer <NUM>, and second non-implanted region <NUM> in fourth doping semiconductor layer <NUM> is electrically connected to contact <NUM> through electrode layer <NUM> as well. <FIG> illustrates a top view of LED structure <NUM> after forming electrode layer <NUM>. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>. Electrode layer <NUM> electrically connects second doping semiconductor layer <NUM> or fourth doping semiconductor layer <NUM> and contacts <NUM> and forms an electrical path to connect the LED units with the driving circuit in first substrate <NUM>. The driving circuit may control the voltage and current level of first LED unit <NUM>, second LED unit <NUM> and third LED unit <NUM> through contacts <NUM> and electrode layer <NUM>. In some implementations, electrode layer <NUM> may include conductive materials, such as indium tin oxide (ITO), Cr, Ti, Pt, Au, Al, Cu, Ge or Ni.

Then, as shown in <FIG> and <FIG>, color conversion layer <NUM> is formed on first LED unit <NUM>. <FIG> illustrates a top view of LED structure <NUM> after forming color conversion layer <NUM>. <FIG> illustrates a cross section of LED structure <NUM> along line A-A' in <FIG>, and <FIG> illustrates a cross section of LED structure <NUM> along line B-B' in <FIG>. Color conversion layer <NUM> converts light of the first color to a third color. In some implementations, color conversion layer <NUM> may include phosphor. In some implementations, color conversion layer <NUM> may include quantum dots. In some implementations, color conversion layer <NUM> may be formed on first LED unit <NUM> by printing technology. In some implementations, color conversion layer <NUM> may be formed on first LED unit <NUM> by the photolithography process. It is understood that the descriptions of the material and the manufacture method of color conversion layer <NUM> are merely illustrative and are not limiting, and those skilled in the art can change according to requirements.

By forming color conversion layer <NUM> on first LED unit <NUM> to convert the first color emitted by first LED unit <NUM> to the third color, LED structure <NUM> can emit at least three different colors. When individually applying different bias voltages to first LED unit <NUM>, second LED unit <NUM>, and third LED unit <NUM> (three sub-pixels), the three primary colors, e.g., red, green and blue, may integrally form a full color pixel.

<FIG> illustrates a top view of an exemplary LED structure <NUM>, according to some implementations of the present disclosure. In the implementation shown in <FIG>, a full color pixel may include more than three sub-pixels. For example, as shown in <FIG>, LED structure <NUM> forms a full color pixel in a display, and LED structure <NUM> includes four sub-pixels, LED unit <NUM>-<NUM>. For example, LED units <NUM>, <NUM>, and <NUM> may be formed in the first semiconductor layer, and LED unit <NUM> may be formed in the second semiconductor layer. LED units <NUM>, <NUM>, and <NUM> may emit blue light, and LED unit <NUM> may emit green light. Then the color conversion layer is formed on LED unit <NUM> to convert the color of LED unit <NUM> from blue light to red light. Hence, the full color pixel formed by LED structure <NUM> includes one green sub-pixel, one red sub-pixel, and two blue sub-pixels.

<FIG> illustrates a top view of three exemplary LED structures <NUM>, <NUM> and <NUM>, according to some implementations of the present disclosure. LED structures <NUM>, <NUM> and <NUM> each have sub-pixels arranged in a different pattern to form the various pixels in the respective LED structures. As shown in <FIG>, the arrangement of the sub-pixels in the full color pixel may be various. For example, LED structure <NUM> includes a plurality of pixels, and each pixel includes three sub-pixels. The arrangement of the sub-pixels in each pixel are repeated in LED structure <NUM>. For another example, LED structure <NUM> also includes a plurality of pixels, and each pixel also includes three sub-pixels. However, the arrangement of sub-pixels in each pixel is interlaced. More specifically, the arrangement of sub-pixels in adjacent pixels in LED structure <NUM> rotates <NUM> degrees. For a further example, LED structure <NUM> also includes a plurality of pixels, and each pixel also includes three sub-pixels. However, the arrangement of sub-pixels in adjacent pixels in LED structure <NUM> rotates <NUM> degrees. It is understood that the arrangements and the number of sub-pixels in a full color pixel or the arrangements of multiple full color pixels in a display are not limiting, and those skilled in the art can make changes according to requirements.

The present disclosure utilizes first ion-implanted material <NUM> to isolate first LED unit <NUM> and second LED unit <NUM> and define the light emitting area of first LED unit <NUM> and second LED unit <NUM>. Therefore, the top surface of first semiconductor layer <NUM> may be kept substantially flat, and second semiconductor layer <NUM> could be formed or bonded on first semiconductor layer <NUM>. Furthermore, the present disclosure utilizes different materials to form first semiconductor layer <NUM> and second semiconductor layer <NUM>, and first LED unit <NUM> and second LED unit <NUM> emits light of a first color, and third LED unit <NUM> emits light of a second color. Then, color conversion layer <NUM> is formed on first LED unit <NUM> to convert the first color emitted by first LED unit <NUM> to the third color. When applying bias voltages to first LED unit <NUM>, second LED unit <NUM>, and third LED unit <NUM> (three sub-pixels), the three primary colors, e.g., red, green and blue, may integrally form a full color pixel.

Implementations of the present disclosure include the stacking structure of multiple semiconductor layers to manufacture LED units emitting light of at least two colors. The color conversion layer converts on of the at least two colors to the third color, and therefore the LED structure disclosed can achieve full color light emission by multiple LED units while avoiding the drawbacks of mass transfer of the LED units.

The foregoing description of the specific implementations can be readily modified and/or adapted for various applications.

Claim 1:
A light emitting diode (LED) structure, comprising:
a substrate (<NUM>); and
a plurality of LED units formed on the substrate (<NUM>), each LED unit comprising:
a first doping semiconductor layer (<NUM>);
a multiple quantum well (MQW) layer (<NUM>) formed on the first doping semiconductor layer (<NUM>); and
a second doping semiconductor layer (<NUM>) formed on the MQW layer (<NUM>),
wherein the plurality of LED units comprise a first LED unit (<NUM>) and a second LED unit (<NUM>) formed on the substrate (<NUM>) and horizontally adjacent to each other,
wherein the second doping semiconductor layer (<NUM>) of the first LED unit (<NUM>) is electrically isolated with the second doping semiconductor layer (<NUM>) of the second LED unit (<NUM>) by an ion-implanted material formed above the first doping semiconductor layer (<NUM>) and the MQW layer (<NUM>),
wherein the plurality of LED units further comprises a third LED unit (<NUM>) formed above the ion-implanted material,
the first LED unit (<NUM>) and the second LED unit (<NUM>) are configured to emit light of a first color, the third LED unit (<NUM>) is configured to emit light of a second color different from the first color, and
wherein a color conversion layer (<NUM>) is formed on the first LED unit (<NUM>) to convert light of the first color to light of a third color different from the first color and the second color.