CN211404520U

CN211404520U - LED chip structure

Info

Publication number: CN211404520U
Application number: CN202020353277.3U
Authority: CN
Inventors: 安金鑫; 周充祐; 李刘中; 林子平; 郑士嵩
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Priority date: 2020-03-19
Filing date: 2020-03-19
Publication date: 2020-09-01
Anticipated expiration: 2030-03-19

Abstract

The utility model relates to a semiconductor field specifically is a LED chip structure, it includes growth substrate, be formed at epitaxial layer on the growth substrate is formed at 2 pads on the epitaxial layer, the pad is the metal bonding pad, the cross sectional area of epitaxial layer by growth substrate to the direction of pad reduces, makes the longitudinal section of epitaxial layer is trapezoidal shape, be formed with light shield layer or reflector layer on the side surface of epitaxial layer. The epitaxial layer of LED chip is trapezoidal shape, is favorable to following light resistance or reflection stratum, makes LED chip side can not the light-emitting, follows light resistance or reflection stratum at trapezoidal side and can not increase the volume of LED chip, does not receive the restriction of LED interval, can not influence LED luminous efficacy, prevents RGB LED colour mixture and increases the light-emitting uniformity.

Description

LED chip structure

Technical Field

The utility model relates to a semiconductor field especially relates to a LED chip structure.

Background

The LED light-emitting chip is a core component of the LED lamp, namely a P-N junction. The main functions are as follows: the electric energy is converted into light energy, and the main material of the chip is monocrystalline silicon. The semiconductor wafer is composed of two parts, one of which is a P-type semiconductor in which holes predominate and the other of which is an N-type semiconductor in which electrons predominate. When the two semiconductors are connected, a P-N junction is formed between them. When current is applied to the wafer through the wire, electrons are pushed to the P region where they recombine with holes and then emit energy in the form of photons, which is the principle of LED light emission. The wavelength of the light, i.e., the color of the light, is determined by the material forming the P-N junction.

Generally, an epitaxial layer (generally including an n-type semiconductor, a p-type semiconductor, and a light emitting layer) is prepared on a growth substrate, and then a separate LED chip is obtained by photolithography, etching, grinding, and cutting, and then the separate LED chip is processed by transfer soldering, etc. to form an optical system such as a display, a backlight, etc.

At present, the light-emitting surface of an LED chip has a vertical light-emitting surface perpendicular to the surface of the LED, and also has a lateral light-emitting surface horizontal to the surface of the LED, and the lateral light-emitting surface may have some adverse effects on, for example, direct display products, backlight products, vehicles, and lighting.

At present, a light-blocking light resistor is added after a Mini LED display screen die bonding process, and the main purpose is to prevent RGB LED color mixing and increase light emitting consistency. However, if the film pressing and film pasting processes are performed, the light blocking photoresist covers the surface of the LED, which affects the light emitting efficiency; if the dispensing process is performed, when the LED pitch is small, the light blocking photoresist coverage uniformity cannot be controlled, and color mixing cannot be effectively prevented.

SUMMERY OF THE UTILITY MODEL

Based on above problem, the utility model provides a LED chip structure, its epitaxial layer side design layer or the light reflection stratum that is in the light, its concrete structure as follows:

the utility model provides a LED chip structure, its includes growth substrate, forms in epitaxial layer on the growth substrate, forms in 2 pads on the epitaxial layer, the pad is the metal pad, the cross sectional area of epitaxial layer by growth substrate to the direction of pad reduces, forms trapezoidal shape, be formed with light shield layer or reflection stratum on the side surface of epitaxial layer.

Furthermore, the epitaxial layer comprises a first semiconductor layer, an active layer and a second semiconductor layer, the first semiconductor layer and the second semiconductor layer are N-type semiconductor layers or P-type semiconductor layers, and the types of the first semiconductor layer and the second semiconductor layer are different.

Furthermore, the material of the bonding pad is one of gold, nickel/gold alloy or ITO.

Further, the reflective layer is a bragg reflective layer.

Furthermore, the Bragg reflection layer is formed by alternately laminating at least one layer of titanium oxide and at least one layer of silicon dioxide.

Furthermore, the light shielding layer is a photoresist to form a photoresist layer.

Further, the light resistance layer is black or white.

The beneficial effects of the utility model reside in that:

the epitaxial layer of LED chip is trapezoidal shape, is favorable to following light resistance or reflection stratum, makes LED chip side can not the light-emitting, follows light resistance or reflection stratum at trapezoidal side and can not increase the volume of LED chip, does not receive the restriction of LED interval, can not influence LED luminous efficacy, prevents RGB LED colour mixture and increases the light-emitting uniformity.

Drawings

FIG. 1 is a schematic structural view of an LED chip of embodiment 1;

FIG. 2 is a schematic view of an epitaxial layer structure of example 1;

FIG. 3 is a manufacturing flow chart of example 1;

FIG. 4 is a diagram of a corresponding structural variation in the flow of FIG. 3;

FIG. 5 is a schematic structural view of an LED chip of embodiment 2;

FIG. 6 is a manufacturing flow chart of example 2;

fig. 7 is a diagram of a corresponding structural change in the flow of fig. 6.

The reference numbers in the figures illustrate:

the semiconductor device includes a growth substrate 10, an epitaxial layer 20, a first semiconductor layer 21, an active layer 22, a second semiconductor layer 23, a light shielding layer 24, a reflective layer 25, a pad 30, a photoresist 40, and a mask 50.

Detailed Description

The technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the drawings in the embodiments of the present application, and the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments.

The terms "first" and "second" in this application are used for descriptive purposes only and are not to be construed as indicating or implying a relatively significant or implied number of technical features indicated by the nomenclature. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Example 1

As shown in fig. 1 and 2, a specific structure of the LED chip described in embodiment 1 is shown. The semiconductor structure comprises a growth substrate 10 and an epitaxial layer 20 formed on the growth substrate 10, wherein the epitaxial layer 20 is composed of a first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23, wherein the first semiconductor layer 21 and the second semiconductor layer 23 are N-type semiconductor layers or P-type semiconductor layers, which are different from each other, that is, if the first semiconductor layer 21 is an N-type semiconductor layer, the second semiconductor layer 23 is a P-type semiconductor layer.

The growth substrate 10 is used for growth of an epitaxial layer, and the growth substrate 10 used is distinguished according to the emission wavelength of the LED chip. Sapphire, SiC, Si, and the like are used as substrates in the case of LED chips of GaN-based semiconductor materials such as blue LED chips and white LED chips, and GaAs and the like are used as substrates in the case of LED chips of AlInGaP-based materials such as red LEDs. The reason why the different substrate is used depending on the light emission wavelength of the LED chip is to select an inexpensive substrate material having a lattice constant as close as possible to the lattice constant of the light emitting portion (semiconductor) crystal of the LED chip. By doing so, the difference in lattice constant (lattice mismatch) is narrowed, and the possibility of crystal defects that hinder light emission in the semiconductor layer is reduced. And the unit price of the LED chip can be reduced. Further, an expensive GaN substrate is used for an element having a high current density and a high light output density such as a blue-violet semiconductor laser. Note that the GaN substrate is also used for part of the blue LED.

Two bonding pads 30 are formed on the epitaxial layer 20, and the bonding pads are made of Ni-Au alloy and have good conductivity and mechanical properties.

The epitaxial layer 20 is a specific single crystal thin film grown on the growth substrate 10 at an appropriate temperature. A P-N junction is formed between the first semiconductor layer 21 and the second semiconductor layer 23 on the epitaxial layer, and the first semiconductor layer 21 and the second semiconductor layer 23 are respectively formed with a bonding pad 30, and applying a voltage between the first semiconductor layer 21 and the second semiconductor layer 23 through the bonding pads can emit energy (and light waves) in the form of photons in the active layer 22, and the wavelengths of the light waves emitted by the active layer 22 are different due to the different materials of the active layer 22, so that the LED chip emits light with different colors.

The epitaxial layer 20 has a trapezoidal shape in which the cross-sectional area gradually decreases in the direction from the growth substrate to the pad 30, so that the side surface of the epitaxial layer 20 is a downward inclined surface and the longitudinal section thereof is trapezoidal.

A light-shielding layer 24 is formed on the surface of the epitaxial layer 20, and the light-shielding layer 24 is a photoresist.

The longitudinal section of the epitaxial layer 20 is trapezoidal, the side face of the epitaxial layer is a downward inclined face, the inclined face is easier to be connected with the light shielding layer 24, the connection between the light shielding layer 24 and the inclined face is more unstable usually, when the light shielding layer 24 is connected, the thickness of the light shielding layer 24 is the same, and for the epitaxial layer 20, the inclined face does not increase the whole width of the epitaxial layer 20 too much, so that the miniaturization of a chip is facilitated, and the problem of LED spacing is not considered after the light shielding layer 24 is formed.

As shown in fig. 3 and 4, the specific steps of the preparation of the LED chip are as follows:

and (S10) photoresist coating.

Providing a growth substrate 10, wherein a plurality of epitaxial layers 20 are formed on the growth substrate, two bonding pads 30 are arranged on each epitaxial layer 20, and the bonding pads 30 are used for packaging the subsequent LED chip. The photoresist 40 is coated on the growth substrate 10, the epitaxial layer 20 and the bonding pad 30 by spin coating, the photoresist 40 covers the whole growth substrate 10, the epitaxial layer 20 and the bonding pad 30, and the surface is uniform and flat after drying. The photoresist 40 is preferably white or black.

The epitaxial layer 20 is a plurality of single crystal thin films, a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23, which are grown on the growth substrate 10 in sequence, and the thickness of each layer is usually in the nanometer order to ensure the miniaturization of the LED chip. The growth method includes Vapor Phase Epitaxy (VPE), Liquid Phase Epitaxy (LPE), molecular beam epitaxy (MPE), Plasma Enhanced Chemical Vapor Deposition (PECVD), and metal organic compound vapor phase epitaxy (MOCVD).

S11 dry etches away part of the photoresist.

A portion of the photoresist 40 is removed by dry etching to expose the epitaxial layer 30 and the bonding pad 30. Leaving a portion of the photoresist layer 40 substantially flush with the surface of the epitaxial layer 20.

S12 cuts the photoresist.

A portion of the photoresist 40 is cut away to leave a certain thickness of the photoresist on the side surface of the epitaxial layer 20, thereby obtaining the light shielding layer 24. Therefore, no light leaks out of the side surface of the LED chip when the LED chip is used.

S13 dicing the growth substrate.

The growth substrate 10 is cut to obtain individual LED chip units.

The cutting of the photoresist 40 and the cutting of the growth substrate 10 need to be performed in two steps, because the two materials are different, different jigs and cutting methods are needed, and the cutting needs to be performed by adjusting process parameters. The cutting photoresistance 40 can be cut by etching or laser, the cutting growth substrate can be cut by laser or laser and splitting, and after cutting, the processes of point measurement, sorting, inspection and the like are carried out.

In the step of cutting the photoresist at S12, the photoresist may be removed by exposure/development or etching.

Example 2

Fig. 5 shows a specific structure of the LED chip of this embodiment. The semiconductor structure comprises a growth substrate 10 and an epitaxial layer 20 formed on the growth substrate 10, wherein the epitaxial layer 20 is composed of a first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23, wherein the first semiconductor layer 21 and the second semiconductor layer 23 are N-type semiconductor layers or P-type semiconductor layers, which are different from each other, that is, if the first semiconductor layer 21 is an N-type semiconductor layer, the second semiconductor layer 23 is a P-type semiconductor layer.

Two bonding pads 30 are formed on the epitaxial layer 20, and in this embodiment, the material of the bonding pads is preferably an ITO thin film, which is a metal oxide material having high electrical conductivity, high visible light transmittance, high mechanical hardness and good chemical stability. The ITO film is a bonding pad material of the LED chip which is applied more at present.

The ITO thin film is etched to obtain the bonding pad 30 by depositing IOT material on the epitaxial layer 20.

The epitaxial layer 20 has a trapezoidal shape in which the cross-sectional area gradually decreases in the direction from the growth substrate to the pad 30, and thus the side surface of the epitaxial layer 20 is a downward inclined surface and the longitudinal section thereof is trapezoidal.

A reflective layer 25 is formed on the side surface of the epitaxial layer 20, and the reflective layer 25 is a bragg reflective layer. The Bragg reflector is a reflector structure comprising an adjustable multilayer structure composed of two optical materials, and can reflect light well under a very thin thickness to prevent the light from penetrating out of the side surface of the LED chip. In this embodiment, the bragg reflector layer is formed by alternately laminating a plurality of titanium oxide layers and a plurality of silicon dioxide layers.

As shown in fig. 6 and 7, the LED chip manufacturing method according to this embodiment includes:

and (S20) photoresist coating.

Providing a growth substrate 10, wherein a plurality of epitaxial layers 20 are formed on the growth substrate, two bonding pads 30 are arranged on each epitaxial layer 20, and the bonding pads 30 are used for packaging the subsequent LED chip. A photoresist 40 is coated on the growth substrate 10, the epitaxial layer 20 and the pad 30 by spin coating, and the photoresist 40 covers the entire growth substrate 10, the epitaxial layer 20 and the pad 30, and then dried.

S21 covers the patterned mask.

Covering the patterned mask 50 on the photoresist 40, wherein if the photoresist 40 is a positive photoresist, the region of the mask 50 corresponding to the position right above the reflective layer 25 is a region that can transmit light; if the photoresist 40 is a negative photoresist, the region of the mask 50 corresponding to the position directly above the reflective layer 25 is a region that is not transparent to light. The photoresist 40 of this embodiment is a positive type photoresist.

And S22, exposing and developing.

The structure obtained in step S21 is placed in an exposure-only machine, and then the mask 50 is removed and developed with a developer, and the photoresist 40 on the mask 50 in the region corresponding to the position directly above the reflective layer 25 is removed to expose the side surface of the epitaxial layer 20.

S23 depositing a reflective layer.

The reflecting layer 25 is obtained by depositing alternating layers of titanium dioxide and titanium oxide on the lateral surface of the epitaxial layer 20 by means of physical vapor deposition or chemical vapor deposition.

S24 removes the photoresist.

The remaining photoresist 40 is removed completely, and the photoresist 40 can be removed by laser cutting or etching to leave the reflective layer 25 attached to the side surface of the epitaxial layer 20, so as to prevent light from penetrating through the side surface of the LED chip during use.

S25 is cut into individual LED chips.

The growth substrate 10 is cut into individual units by laser or laser-plus-cleavage to obtain LED chips.

In this embodiment, the side surface of the epitaxial layer 20 is covered by the reflective layer 25, and the reflective layer 25 is a bragg reflective layer, which has excellent optical performance and can prevent light from passing through the side surface of the epitaxial layer 20 by only a thin film.

In the embodiment, the reflective layer 25 is formed by depositing the bragg reflective layer, the reflective layer 25 is thin and is attached to the side surface of the epitaxial layer 20, the reflective layer 25 does not additionally increase the width of the epitaxial layer 20, and the problem of the mounting distance of the LED is not considered. It should be noted that the shape of the reflective layer 25 in fig. 4 and 5 does not represent the shape in actual manufacturing, and the illustration is only a schematic diagram, and the thickness of the reflective layer 25 tends to be uniform at all positions on the side surface of the epitaxial layer 20 in actual manufacturing.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.

Claims

1. The utility model provides a LED chip structure, its characterized in that includes growth substrate, is formed in epitaxial layer on the growth substrate, be formed in 2 pads on the epitaxial layer, the pad is the metal pad, the cross sectional area of epitaxial layer by the growth substrate to the direction of pad reduces, makes the longitudinal section of epitaxial layer is trapezoidal shape, be formed with light shield layer or reflection stratum on the side surface of epitaxial layer.

2. The LED chip structure of claim 1, wherein said epitaxial layer comprises a first semiconductor layer, an active layer and a second semiconductor layer, said first semiconductor layer and said second semiconductor layer are N-type semiconductor layer or P-type semiconductor layer, said first semiconductor layer and said second semiconductor layer are different types of semiconductor layers.

3. The LED chip structure of claim 1, wherein the bonding pad is made of one of gold, nickel/gold alloy, or ITO.

4. The LED chip structure of claim 1, wherein said reflective layer is a bragg reflective layer.

5. The LED chip structure of claim 4, wherein said bragg reflector layer is an alternating stack of at least one layer of titanium oxide and at least one layer of silicon dioxide.

6. The LED chip structure of claim 1, wherein said light-shielding layer is a photoresist-forming photoresist layer.

7. The LED chip structure of claim 6, wherein said light-blocking layer is black or white.