TWI241031B - Light-emitting diode device - Google Patents

Abstract

The present invention relates to a light-emitting diode (LED) device, whose manufacturing method comprises: firstly, growing an n-GaN layer on the substrate surface; growing SiO2 on the surface of the n-GaN layer; and exposing the n-GaN in the mesa region by a photolithography process; growing the LED structure epitaxially in the mesa region by MOCVD; growing the structure having p-n on the same side by using the characteristics of selective growing GaN locally; and fabricating the electrode on the structure to form the LED. Etching is not necessary in the present invention to complete the structure having p-n on the same side. Its process is effectively simplified in comparison with the fabrication of the GaN LED in the prior art. Furthermore, the problems of non-uniform etching depth due to etching, over-rugged surface, bad electrical characteristics resulted from etching damage and leakage current can be avoided. In addition, SiO2 also functions as the scattering layer. Since its formation has the scattering effect, the light emitted from the light-emitting layer varies its path through the scattering of the scattering layer, so as to reduce the total internal reflection. Therefore, the LED of the present invention has a better efficiency in comparison with the device of the prior art.

Description

1241031

[Technical field to which the invention belongs] The present invention relates to one type of light emission mainly composed of an n-GaN layer. In addition, the present invention relates to another type of electrode composed of an I n A GaN layer. ~ [Prior art]

Because most gallium nitride series semiconductor materials are mainly grown on conductive sapphire substrates, when manufacturing LED elements, two = J =: the poles are on the same side, but the wet etching used in the past is not common for W queue materials. Not applicable. Because of its strong acid and alkali resistance, the general wet etching is too slow for the gallium nitride series materials. Therefore, dry etching has been used in the past, such as international patent case number $ WOO9854757 That is, a method of dry etching is revealed. However, although dry etching can overcome the problem of wet etching, it is easy to damage the adult insect layer. Therefore, the dry type is more and more difficult for the component itself. , Including uneven depth of the engraving, the surface of the engraving is too rough, and the electrical damage caused by the engraving damage is poor, such as the literature (Jomon 〇f

Electronic, 27, No. 4,261, 1998), as well as the leakage current caused by the mesa sidewall of Qian Qian, etc., as described in the literature (Αρρ1.

Phys. Lett. 72, 742, 1 998; Jpn. J. Appl. Phys. 37, LI 202, 1 998), so the problems caused by etching need to be solved in the GaN series LED process.

Page 61241031, description of the invention (2) In addition, 'Because the refractive index between III-V semiconductor GaN (n = 2.3) and air (n = 1) is very different, the critical angle of total reflection is only about 25 degrees, Most of the light caused by the light-emitting layer can only be totally reflected inside and cannot be emitted. In order to change the structure of this interface, some people have proposed to roughen the semiconductor surface to make light pass through the roughened layer interface after emitting from the light-emitting layer. Because the light is scattered, the path of incident light is changed. After total reflection, the light is emitted. The probability also increases, such as the literature (IEEE Transcations on Electron

Devices, 47 (7), 1492, 20000), after the roughening, its external f light efficiency increased significantly to 40%. In the conventional technology, the roughening method is mainly achieved by etching on the epitaxial surface. For example, in US Pat. No. 5,040,044, chemical etching is used to roughen the surface of the light-emitting element to achieve the effect of increasing the luminous efficiency. Other related The patents still have US patents US5429954, US5898 1 92, etc. However, the above-mentioned processing method is only applicable to red LEDs, mainly because its material processing characteristics are relatively simple; it is not applicable to GaN series materials because it has strong It is resistant to acids and alkalis, and although dry etching can overcome the problem of wet etching, it can easily cause damage to the epitaxial layer, especially p-GaN is very easy to cause the resistance value to rise, and p-GaN usually grows very much. It is thin (0.0 · 0.3 // m). If the p-GaN is directly roughened, the light-emitting layer may be damaged, and the light-emitting area may be reduced. In addition, the transparent electrodes generally used on GaN LEDs must be very light-transmissive. Thin (100 nm), so-will cause discontinuity of the transparent electrode, affect the current dispersion, and reduce the luminous efficiency. Therefore, it is difficult to directly roughen p-G a N unless Bu is very thick. In view of the limitations and disadvantages of the above-mentioned related conventional technologies, this case

Page 1241031

V. Description of the invention (3) The wise man went to great lengths to invest in this research based on his many years of experience in related research, and thus the invention came into being. [Summary of the Invention] In order to solve the problems described in the previous part of the "prior art", the present invention proposes a method for exposing n-GaN without etching semiconductor materials, thereby improving the problems caused by etching. The present invention discloses a method for manufacturing a GaN series light-emitting element. Compared with a light-emitting element without using the present invention, the light-emitting element manufactured by the present invention can avoid various problems caused by etching.

In the present invention, an interface layer Si02 is added to the surface of a wafer that has been grown stupidly. Η02 'is used to make mesa on the surface by using a yellow light lithography process, and Si 02 in the mesa region is removed to expose the n-GaN layer. The light emitting diode structure was epitaxially grown in the mesa region by M0CVD, and the characteristics of the selective growth of the gallium nitride epitaxial layer were used to grow it into a p-n coplanar structure. Finally, the Si 02 was removed to obtain The ρ-η is on the same surface as the light emitting diode structure. Therefore, the present invention does not need to use an etching process to complete the structure of the pn on the same surface required for the LED element, so various problems caused by etching can be avoided. In addition, in order to solve the problem of internal total reflection described in the rear part of the "Previous Technology" above, the present invention also discloses a method of using a method of partially filling the SiO2 layer in the InAlGaN layer during the epitaxial process to achieve a rough scattering effect.

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V. Description of the invention (4) The result is to improve the luminous efficiency of GaN series light-emitting devices. The invention discloses a method for achieving a roughening effect without roughening p-GaN in a GaN series light-emitting element. Compared with a light-emitting element without using the present invention, the light-emitting element produced by the present invention does not need to be damaged p-G a N or the light emitting layer can significantly improve the light emitting efficiency. In the present invention, after a stupid crystal first grows InAlGaN, a yellow light lithography process is used to form a groove on its surface, and a local area is removed and the substrate is exposed, and a Si02 layer is grown in this groove, and then a light emitting diode is grown on it Polar body structure to form a light-emitting diode element · Using this S i 02 when the characteristics of the scattering layer make it have a scattering effect 'so that the light emitted from the light-emitting layer passes through the scattering effect of this scattering layer to reduce total reflection, To improve luminous efficiency. The features and advantages of the present invention will be better understood from the following detailed description of the preferred embodiments and with reference to the accompanying drawings. [Embodiment] Embodiment 1. In order to implement the purpose and content described in the previous part of the "Inventive Content" above, the present invention adopts the following method: Please refer to Fig. 1. First, place the sapphire substrate (1) in the MOCVD system. Medium, a 20 to 50 nm thick GaN buffer layer (2) was grown at 50 0 to 60 0 ° C, and then the substrate temperature was raised to 1000

1241031 V. Description of the invention (5) --- 1200 C Grow a layer of Si doped GaN with a thickness of 2 ~ 4 / zm, and then take out day and day j, and grow 0.5 ~ ium Si02 in PECVD. 3) Then use the yellow light lithography process to place the mesa area (4). 〇2 removed, and then this wafer was placed in a 70 0 X: ~ 90 (rc CVD system, the InGaN / GaN multiple quantum well structure (5) was grown as a light-emitting layer, and then the substrate temperature was raised to 1000 ° C ~ 1200 ° C grow a layer of 〇 ·; [~ 〇 · 2 // in thickness of Mg doped GaN contact layer, and finally take out this wafer and remove SiO2 outside the mesa area. Light emitting diode wafer (10) on the same surface. Ni / Au metal is made on p-GaN surface as p-type ohmic contact electrode (7), and Ti / Al metal is made on n-GaN surface as n-type. The ohmic contact electrode (8) can be prepared as described above to complete the grain structure of the present invention. Example 2 In addition, in order to specifically implement the purpose and content described in the latter part of the "inventive content" above, the present invention adopts the following method : Please refer to Figure 2. First, place the sapphire substrate (11) in the M0CVD system and grow a layer> 0 · 1 // m thick InAlGaN layer (12), then take out the wafer and use the yellow light lithography process and dry etching on Trenches (14) are etched in the I nA 1 GaN buffer layer. The depth is the thickness of the InAlGaN layer, then Si02 (1 3) is grown in this trench, and the wafer is placed in MOCVD again, and the substrate temperature is raised to 800 ~ 120 (TC grows a layer of Si 2 // m thick Si). -doped of

InAlGaN layer, then lower the substrate temperature to 700 ° C ~ 90 (TC, grow

Page 10 1241031 V. Description of the invention (6)

InGaN / GaN multiple quantum well structure (15) is used as a light emitting layer, and then the substrate temperature is raised to 100 ° C ~ 1200 ° C to grow a layer of GaN contact with a thickness of 0 · b 0 · 2 // πιm Layer (16), so that the light emitting diode wafer (20) is completed. A part of p-GaN (1 6) and quantum well structure (1 5) were removed from this epitaxial wafer by a dry etching method, and the n-GaN surface was exposed, and then Ni / Au metal was fabricated on the p-GaN surface as a p-type Ohm contact electrode (17), and Ti / Al metal is made on η-GaN surface as !! The ohmic contact electrode (18) is manufactured as described above to complete the grain structure of the present invention. Embodiment 3. Please refer to FIG. 3, first place an apphire substrate (21) in a MOCVD system, and grow a layer of > 〇 · 1 // ηι thick InAlGaN layer (22) thereon, and then take out the wafer and use it The yellow light lithography process and dry etching etch a trench (24) on the InA1GaN buffer layer. The depth of the trench exceeds the thickness of the InAlGaN layer by more than 0 · 2 ~ 5 // m, and then SiO2 is grown in this trench (23). Then, the wafer was placed in MOCVD again, and the substrate temperature was raised to 800-1200 ° C to grow a layer of SiAl-doped InAlGaN with a thickness of 1 to 2 / zm, and then the substrate temperature was reduced to 70 0 ° C. ~ 90 0 ° C, grow InGaN / GaN multiple quantum well structure (25) as light emitting layer, and then raise the substrate temperature to 1000 ° C ~ 1200 ° C to grow a layer of 0.1 ~ 0.2 // m thick Mg- The doped GaN contact layer (26), so that the light emitting diode wafer (30) is completed. A part of p-GaN (26) and quantum well structure (25) were removed from this epitaxial wafer by a dry etching method, and ^ GaN surface was exposed. Then, Ni / Au metal was fabricated on the p-GaN surface as a p-type ohmic junction.

Page 111241031 V. Description of the invention (7) The contact electrode (27), and Ti / Al metal is made on the n-GaN surface as the n-type ohmic contact electrode (2 8). Grain structure.

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Schematic illustrations Exemplary schematics are GaN-based; InAlGaN is an outline schematic; InAlGaN is the main schematic. Figures 1 (a) to 1 (e) are the outline of the manufacturing process of the light emitting diode element according to the first implementation of the present invention. Figures 2 (a) to 2 (f) are the main light emission according to the second implementation of the present invention. ; Figures 3 (a) to 3 (f) of the manufacturing process of a polar element is a summary of the manufacturing process of a light emitting diode element according to the third implementation of the present invention;

[Description of element symbols] 1 substrate 2 GaN layer 3 S i 0 2 region 4 mesa region 5 multiple quantum well structure 7 P-type ohmic contact electrode 8 η-type ohmic contact electrode 10 light-emitting diode epitaxial wafer 11 substrate 12 InAlGaN layer 13 Si02 Region 14 Trench 15 Multiple quantum well structure 16 GaN contact layer Page 13 1241031

Brief description of drawings on page 14 17 p-type ohmic contact electrode 18 n-type ohmic contact electrode 20 light-emitting diode worm wafer 21 substrate 22 InAlGaN layer 23 Si02 region 24 trench 25 multiple quantum well structure 26 GaN contact layer 27 p-ohmic Contact electrode 28 η-type ohmic contact electrode 30 Light emitting diode chip

Claims (1)

1241031 _ Case No. 92129342_ Years and months Amendment _ 6. Scope of patent application The barrier layer contains at least one of SiO 2, SiN, AIN, TiN, A120 3 or a combination thereof. 6. The light-emitting diode device according to item 1 of the patent application scope, wherein the barrier layer is one of a metal, an alloy, or a combination thereof. 7. The light-emitting diode device according to item 1 of the application, wherein the barrier layer is made by growing in E-Gun, Sputter, or CVD. 8. The light emitting diode element according to item 1 of the patent application scope, wherein the thickness of the barrier layer is 0.1 μm or more. 9. The light-emitting diode device according to item 1 of the patent application scope, wherein the mesa area is made by a yellow light lithography process. 10. The light-emitting diode element according to item 1 of the patent application scope, wherein the light-emitting active layer may have a structure such as a P-N junction, DH, SQW, or MQW. Page 16