Deep ultraviolet thin film semiconductor device structure and manufacturing method thereof
Technical Field
The invention relates to a manufacturing method of a semiconductor light-emitting device, in particular to a deep ultraviolet LED thin film semiconductor device structure and a manufacturing method thereof.
Background
In recent years, in order to improve the light emitting power and efficiency of group III nitride based compound semiconductor light emitting devices, a thin film device technology based on substrate transfer has been developed, such as depositing a group III nitride thin film on a sapphire substrate by MOCVD, then bonding the group III nitride thin film to a semiconductor or metal substrate by a wafer bonding technology or an electroplating technology, and then removing the sapphire substrate by a laser lift-off method; or depositing a III nitride film on the SiC or Si substrate, then bonding the III nitride film on a semiconductor or metal substrate by a wafer bonding technology or an electroplating technology, and then removing the SiC or Si substrate by a chemical etching method.
With the development of high power LEDs and deep ultraviolet LEDs in large quantities, the goal is gradually shifted to the development of flip film chips (Thin film flip chips). The flip-chip film chip can achieve high luminous efficiency, mainly lies in that the crystal layer is arranged below, and is packaged on the substrate by utilizing metal materials, so that the heat in the crystal layer can be effectively removed, and because no connecting material is needed, the stability is relatively high, and the flip-chip film chip can be used for large-current and large-scale elements for illumination. Due to the wide band gap of the deep ultraviolet LED, the generated deep ultraviolet light can absorb a lot of materials, so that the reduction of the material absorption has important significance on the efficiency and the reliability of a deep ultraviolet LED device. The problems of more epitaxial defects, low luminous efficiency and the like of the existing deep ultraviolet LED cause that heat treatment has high requirements on the efficiency of an LED device.
Disclosure of Invention
The invention provides a deep ultraviolet thin film semiconductor device structure and a manufacturing method thereof, wherein a heat dissipation hollow column structure corresponding to a pattern substrate is arranged between a substrate and an epitaxial layer, so that the light extraction is increased and the heat dissipation effect is improved.
According to a first aspect of the present invention, a deep ultraviolet thin film semiconductor device structure includes a light transmissive substrate, a deep ultraviolet light emitting epitaxial layer, a connection structure, and an insulating heat dissipation substrate, which are sequentially disposed from bottom to top; the light-transmitting substrate is provided with a plurality of grooves with openings at the bottom, the deep ultraviolet light-emitting epitaxial layer comprises a buffer layer, an n-type semiconductor layer, a light-emitting active layer and a p-type semiconductor layer which are sequentially arranged, wherein the buffer layer is grown on the light-transmitting substrate and the thickness of the buffer layer is larger than the depth of the grooves; the buffer layer is arranged in the groove, and the buffer layer is arranged in the groove and is provided with a plurality of openings corresponding to the openings of the groove.
Preferably, the plurality of grooves are periodically distributed in a pattern.
Preferably, the depth of the hollow column structure is 0.1 um-5.0 um, and the diameter is 0.01 um-1 um.
Preferably, the groove is a downward-depressed hemispherical shape, a trapezoidal shape, or a rectangular shape.
Preferably, the light wavelength generated by the luminous active layer is between 100nm and 400nm
Preferably, the connection structure comprises a p-bonding layer, an n-bonding layer and an insulating layer, wherein the p-bonding layer is connected with the p-type semiconductor layer and the n-bonding layer is connected with the n-type semiconductor layer, and the insulating layer separates the p-bonding layer and the n-bonding layer; and the p bonding layer and the n bonding layer are led out of the electrodes from the opening of the insulating heat-radiating substrate respectively.
Preferably, the material of the light-transmitting substrate is an AlN single crystal material, sapphire, or GaN; the material of the deep ultraviolet light-emitting epitaxial layer is an aluminum nitride based material.
Preferably, the thickness of the light transmissive substrate is 0.5um to 3.0 um.
According to a second aspect of the present invention, a method of fabricating a deep ultraviolet thin film semiconductor device includes the steps of:
1) providing a light-transmitting substrate, and patterning the light-transmitting substrate to form a plurality of grooves;
2) growing a buffer layer on the light-transmitting substrate, wherein the thickness of the buffer layer exceeds the depth of the groove;
3) sequentially growing an n-type semiconductor layer, a light-emitting active layer and a p-type semiconductor layer to form a deep ultraviolet light-emitting epitaxial layer;
4) defining a single core particle area on the deep ultraviolet light-emitting epitaxial layer, manufacturing a connecting structure, and manufacturing a chip with an inverted structure;
5) bonding a chip to an insulating heat-radiating substrate, and manufacturing an electrode;
6) thinning the light-transmitting substrate to the bottom of the groove;
7) etching the n-type semiconductor layer from the bottom of the groove by a dry etching method to form a hollow column structure penetrating through the insulating layer;
8) dividing the core particles according to the boundary of the chip to form single deep ultraviolet thin film semiconductor device
Preferably, in step 6), the method for thinning the light-transmissive substrate includes mechanical grinding, chemical polishing, dry etching and wet etching.
Preferably, in step 7), the dry etching method includes ICP, RIE and a combination thereof.
The invention has the following beneficial effects:
firstly, a groove structure is manufactured on the growth substrate, and a lateral epitaxial growth mode is combined in epitaxial layer growth, so that the defect density can be effectively reduced; the groove structure substrate graph is correspondingly transferred to the epitaxial buffer layer, a flip chip structure is manufactured, and the light-emitting surface is converted into a convex structure, so that light can be taken out conveniently; furthermore, the hollow column structure is a corresponding periodic graphical structure, has the function of a photonic crystal structure, and can effectively improve the light extraction efficiency; particularly, in the deep ultraviolet light-emitting diode part, the absorption of materials to ultraviolet light can be reduced; in addition, in the manufacturing method of the semiconductor light-emitting device, the growth substrate with the excavated hole is formed, but the continuity of the substrate is kept, so that the method has a supporting effect on a thin film chip structure and reduces the risk of cracking of the epitaxial layer due to overlarge stress.
Drawings
FIG. 1 is a process flow diagram of an embodiment, wherein each step forms a side cross-sectional view of a structure;
FIG. 2 is a top view of a light transmissive substrate having grooves arranged in a matrix;
fig. 3 is a schematic structural view of the deep ultraviolet thin film semiconductor device of the embodiment.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that the above and below relationships between elements in the drawings described herein are understood by those skilled in the art to refer to relative positions of components, and therefore, all components may be inverted to present the same components, and all should fall within the scope of the present disclosure. In other words, the present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the scope of the present invention.
The deep ultraviolet thin film semiconductor device and the manufacturing method thereof are mainly applied to aluminum nitride-based semiconductor light-emitting devices, and are particularly suitable for ultraviolet light-emitting diode devices with the wavelength of 100 nm-400 nm.
As an example, referring to the flowchart of fig. 1, a method of fabricating a deep ultraviolet thin film semiconductor device includes the following steps.
A light-transmitting substrate 100 is provided, and a groove 101 is formed thereon by a combination of dry etching and yellow light processes, wherein the groove 101 is a concave lens with a hemispherical structure and is arranged in a matrix form, and a top view thereof is shown in FIG. 2. The substrate material is preferably AlN single crystal material or sapphire and GaN. Further, the groove 101 may also be trapezoidal, rectangular, etc. The depth of the groove 101 may be, for example, 0.5um to 3.0 um.
Next, on the patterned substrate, sequentially epitaxially growing a buffer layer 210, an n-type semiconductor layer 220, a light emitting active layer 230, and a p-type semiconductor layer 240 to form a deep ultraviolet light emitting epitaxial layer 200; the epitaxial layer is an AlN-based semiconductor material, such as AlN, AlGaN, InAlGaN, or the like. The buffer layer 210 has a thickness greater than the depth of the groove 101, i.e., fills the groove 101 and has a continuous thickness and a flat surface.
Next, a connection structure 300 and a light emitting diode structure with a flip-chip structure are fabricated, including defining the size and electrode area of a single core particle on the light emitting epitaxial layer 200, dry etching to expose the n-type semiconductor layer, and fabricating the p-bonding layer 310 and the n-bonding layer 320, wherein the structure is preferably Ti/Al/Ti/Au/Ti/Ni/Sn, the thickness is between 200 and 5000nm, and may also be made of one alloy of Al, Ag, Ni, Sn, Au, Cu, Ti, Pt, Pd and Rh. The regions outside the p-bonding layer 310 and the n-bonding layer 320 are covered and isolated by an insulating layer 330, preferably SiN for the insulating layer 330. Wherein the p bonding layer 310 and the n bonding layer 320 have an ohmic contact effect and a mirror effect;
next, the structure with the flip chip is bonded to the insulating heat dissipation substrate 400 using high-voltage bonding.
Next, electrode lead voids are formed on the insulating heat-dissipating substrate by laser hollowing or dry etching, and the p-electrode 510 and the n-electrode 520 are filled with plating.
Next, the translucent substrate 100 is polished with high precision, near the bottom of the groove 101. Controlling the etching substrate by combining a dry etching mode, cutting off the buffer layer at the bottom of the groove 101, and opening the bottom of the groove 101, wherein the thickness of the light-transmitting substrate 100 is the same as the depth of the groove 101;
next, by using the substrate with the dug hole as a mask, the buffer layer is etched through to the n-type semiconductor layer 220 corresponding to the bottom opening of the groove 101, so as to form the hollow pillar structure 102. The depth of the hollow column structure 102 is 0.1um to 5.0um, and the diameter is 0.01um to 1 um.
And next, scribing and splitting according to the chip graphic unit by using laser to form a single deep ultraviolet thin film semiconductor device.
As shown in fig. 3, the obtained deep ultraviolet thin film semiconductor device includes a light transmissive substrate 100, a deep ultraviolet light emitting epitaxial layer 200, a connection structure 300, an insulating heat dissipation substrate 400, and p and n electrodes 510 and 520.
The light-transmissive substrate 100 has a plurality of open-bottomed grooves 101 arranged in a periodic matrix. The groove 101 is a hemispherical shape depressed downward. The light-transmitting substrate 100 is mainly used for an epitaxial growth substrate and a light-extracting layer.
The deep ultraviolet light emitting epitaxial layer 200 is located on the light transmissive substrate 100, and includes a buffer layer 210, an n-type semiconductor layer 220, a light emitting active layer 230, and a p-type semiconductor layer 240, which are sequentially disposed. The buffer layer 210 is grown on the transparent substrate 100 and has a thickness greater than the depth of the groove 101, fills the groove 101 and has a certain continuous thickness upward, and has a flat surface. I.e., the bottom of the buffer layer 210 inherits the groove pattern of the patterned arrangement of the growth substrate 100, forming a convex mirror structure of the same patterned arrangement. In addition, other semiconductor layers may be further disposed on/under the respective semiconductor layers, but are not limited thereto. The plurality of hollow pillar structures 102 correspond to the openings of the recess 101 one by one, penetrate through the buffer layer 210, and extend deep into the n-type semiconductor layer 220.
The connection structure 300 is disposed on the deep ultraviolet light emitting epitaxial layer 200 and includes a p bonding layer 310, an n bonding layer 320, and an insulating layer 330, wherein the p bonding layer 310 is connected to the p-type semiconductor layer 240, the n bonding layer 320 is connected to the n-type semiconductor layer 220, and the insulating layer 330 separates the p bonding layer 310 and the n bonding layer 320. The insulating heat-dissipating substrate 400 is bonded to the connection structure 300, and the p-electrode 510 and the n-electrode 520 are connected to the p-bonding layer 310 and the n-bonding layer 320, respectively. The material of the insulating heat dissipating substrate 400 may be an AlN ceramic substrate, SiC, Si, or other heat dissipating substrate. The bonding layer further includes an ohmic contact and a reflective metal, etc. on the semiconductor layer.
In this embodiment, a pattern with a lens effect is formed on a light-transmitting substrate as a reverse light-emitting layer; the manufacturing covers brilliant chip structure on the wafer, with the wafer bonding to insulating heat dissipation base plate on to grind the light transmissivity substrate, form flip-chip film chip structure, utilize the difference of high low position of graphical light transmissivity substrate, adopt the dry etching mode, form the hollow column structure of one deck cavity of graph in the bottom etching, all the other positions remain continuous structure and can reach the effect of supporting the epitaxial layer, hollow column structure can reach photonic crystal's effect and radiating effect simultaneously, can improve light-emitting efficiency.
The above embodiments are only used to further illustrate the deep ultraviolet thin film semiconductor device structure and the manufacturing method thereof, but the present invention is not limited to the embodiments, and any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention fall within the protection scope of the technical solution of the present invention.