CN103489979A - Method for manufacturing semiconductor light emitting devices - Google Patents

Abstract

The invention provides a method for manufacturing semiconductor light emitting devices. Etching technical parameters are changed to enable the dip angle of the side wall of an etched epitaxial layer to be 60-90 degrees, the side wall is almost vertical, and therefore the crack phenomenon of chips in production is avoided, and the productivity is improved.

Description

A kind of preparation method of semiconductor light-emitting device

technical field

The invention relates to the field of optoelectronic devices. More specifically, the present invention relates to a method for manufacturing a semiconductor light emitting device.

Background technique

In the LED chip manufacturing process, the sapphire substrate is the main substrate for GaN-based LED epitaxial growth, and its conductivity and heat dissipation are relatively poor. Due to the poor conductivity of the sapphire substrate, traditional GaN-based LEDs adopt a lateral structure, resulting in current blockage and heat generation. And poor thermal conductivity limits the power of light emitting devices. After the sapphire substrate is removed by laser lift-off technology, the light-emitting diode is made into a vertical structure, which can effectively solve the problem of heat dissipation and light output. In order to improve the light efficiency and power of GaN-based LEDs, the laser lift-off sapphire substrate technology is proposed, that is, after the epitaxial layer is prepared on the sapphire substrate, the epitaxial layer is combined with the supporting substrate, and then the sapphire substrate is removed by laser lift-off method. The device is made into a vertical structure. Before the sapphire substrate is peeled off, the GaN epitaxial layer epitaxially grown on the sapphire substrate is usually etched to produce multiple discrete dies, which facilitates the subsequent chip cutting process and improves production efficiency. At present, the epitaxial layer is usually etched by an inductively coupled plasma (ICP) etching method. The principle of ICP etching is that in the alternating electromagnetic field, the gas generates a discharge phenomenon and enters the plasma state. The plasma acts vertically on the substrate and reacts with it to generate volatile gaseous substances to achieve the purpose of etching. In the ICP process, parameters such as ICP ion source power, radio frequency power, gas flow rate, and chamber pressure will all affect etching. However, the existing ICP process parameters often prevent the plasma from acting vertically on the substrate surface, that is, the sidewall inclination angle obtained by etching is much smaller than 90°, which causes cracks and other phenomena to occur in the subsequent laser lift-off process and reduces the performance of the chip. and production yield.

Contents of the invention

In order to solve the problem of low production yield caused by cracks in the chip due to laser lift-off during the chip production process, the present invention proposes a method for preparing a semiconductor light-emitting device, which includes growing a buffer layer and an N-type GaN layer on a sapphire substrate in sequence , an active layer, a P-type GaN layer to form an epitaxial layer, the method also includes etching the epitaxial layer to expose the sapphire substrate to produce a plurality of discrete tube cores, wherein the etched epitaxial layer has a sidewall inclination angle of 60° ~90°, the method also includes combining the etched epitaxial layer with a supporting substrate, and removing the sapphire substrate by using a laser lift-off method.

Preferably, the inclination angle of the sidewall of the epitaxial layer is 75°-85°. the

Preferably, the method of bonding the etched epitaxial layer to the support substrate is eutectic bonding or curing after glue application.

Preferably, part of the epitaxial layer is reserved between the tube cores as an isolation zone, and at least one of the isolation zones around the tube cores is not connected.

Preferably, the width of the groove between the isolation zone and the edge of the adjacent die is 1-100 microns.

Preferably, the width of the isolation zone is 5-100 microns.

Beneficial effects of the present invention: Compared with the prior art, the present invention provides a method for preparing a semiconductor light-emitting device. In this method, by changing the etching process parameters, the inclination angle of the side wall of the epitaxial layer after etching is 60°-90° °, close to vertical, resulting in fewer slopes, which is more conducive to the subsequent manufacturing process and improves performance and yield. the

Description of drawings

1a and 1b are partial schematic diagrams after the epitaxial layer is etched.

2a-2g are schematic illustrations of the fabrication process of one embodiment of the present invention.

3a-3h are schematic diagrams of the manufacturing process of another embodiment of the present invention.

4a-4g are schematic diagrams of the manufacturing process of another embodiment of the present invention.

5a-5h are schematic diagrams of the manufacturing process of another embodiment of the present invention.

The symbols in the figure illustrate: die 1, isolation zone 2, groove 3, sapphire substrate 100, epitaxial layer 110, support substrate 120, resin glue 210, auxiliary substrate 220, first temporary substrate 310, second temporary substrate 320.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

There are two kinds of epitaxial layer structures after etching in the prior art, as shown in FIG. 1a and FIG. 1b. As shown in FIG. 1a, part of the epitaxial layer is reserved between every two adjacent tube cores 1 as an isolation zone 2, and the isolation zone 2 is discontinuous, and a groove 3 is formed between the isolation zone 2 and adjacent tube cores 1. ; As shown in FIG. 1b, a groove 3 is directly formed between every two adjacent tube cores 1 without an isolation zone.

Embodiment 1 As shown in FIG. 2 a , a buffer layer, an N-type GaN layer, an active layer, and a P-type GaN layer are sequentially grown on a sapphire substrate 100 to form an epitaxial layer 110 . The sapphire substrate 100 is mechanically ground, thinned and polished. As shown in Figure 2b, the epitaxial layer 110 is etched by ICP etching method, the chamber pressure is set to 700mPa, the Cl ₂ , BCl ₃ and Ar gas flow rates are 50 sccm, 10 sccm and 5 sccm respectively, the radio frequency power is 200W, and the ion source power is 500W, etch the epitaxial layer 110 to expose the sapphire substrate 100 to form a plurality of discrete dies 1, and at the same time keep part of the epitaxial layer 110 as the isolation zone 2 between every two adjacent dies 1, different The isolation zone 2 between the tube cores 1 is discontinuous, the width of the isolation zone 2 is 20 microns, and the width of the groove 3 between the edge of the adjacent tube core 1 is 10 microns, and the inclination angle of the side wall of the epitaxial layer after etching is 75°. As shown in FIG. 2 c , the etched epitaxial layer 110 is combined with the supporting substrate 120 by eutectic bonding. The supporting substrate 120 is any one of Si, ceramics, W, Cu, Mo, GaAs, graphite, and glass. As shown in FIG. 2 d , resin glue 210 is coated on the other side of the support substrate 120 , and the resin glue 210 plays a role in relieving stress during the laser lift-off process. In order to make the coated resin glue 210 flat, as shown in FIG. 2e , use a transparent auxiliary substrate 220 such as glass or sapphire to flatten the resin glue 210, then use ultraviolet light to cure the resin glue 210, and remove the auxiliary substrate 220. As shown in FIG. 2f , the sapphire substrate 100 is removed by laser lift-off. As shown in FIG. 2g, the resin glue 210 is removed. The remaining isolation strip 2 is removed, and the P and N electrodes are formed by using a common process to complete the preparation of the semiconductor light emitting device.

In this embodiment, the inclination angle of the side wall of the epitaxial layer is 75°, and the yield rate of chip production is improved.

Embodiment 2 As shown in FIG. 3 a , a buffer layer, an N-type GaN layer, an active layer, and a P-type GaN layer are sequentially grown on a sapphire substrate 100 to form an epitaxial layer 110 . The sapphire substrate 100 is mechanically ground, thinned and polished. As shown in Figure 3b, the epitaxial layer 110 is etched by ICP etching method, the chamber pressure is set to 400mPa, the Cl ₂ , BCl ₃ and Ar gas flow rates are 45 sccm, 15 sccm and 5 sccm respectively, the radio frequency power is 320W, and the ion source power is 600W, etch the epitaxial layer 110 to expose the sapphire substrate 100 to form a plurality of discrete dies 1, and at the same time keep part of the epitaxial layer 110 as the isolation zone 2 between every two adjacent dies 1, different The isolation zone 2 between the tube cores 1 is discontinuous, the width of the isolation zone 2 is 40 microns, and the width of the groove 3 between the edge of the adjacent tube core 1 is 10 microns, and the inclination angle of the side wall of the epitaxial layer after etching is 80°. As shown in FIG. 3 c , a high-temperature epoxy resin modified glue is coated on the etched epitaxial layer 110 , bonded to the first temporary substrate 310 and then cured. As shown in FIG. 3 d , the sapphire substrate 100 is removed by using a laser lift-off method, using a 248 nm excimer laser with a power of 550 mW. As shown in FIG. 3 e , the modified heterocyclic resin glue is coated on the peeling surface and then bonded to the second temporary substrate 320 and cured. As shown in Figure 3f, after protecting the second temporary substrate 320 with wax, the first temporary substrate 310 is etched with hydrofluoric acid plus hydrogen peroxide plus nitric acid (5:2:2), and the high temperature epoxy resin is etched at 100°C with toluene. Resin modified glue. As shown in FIG. 3g, the exposed epitaxial layer is bonded to a supporting substrate 120, which is a silicon substrate. As shown in Figure 3h, the supporting substrate 120 is protected with wax, the second temporary substrate 320 is etched with hydrofluoric acid plus hydrogen peroxide plus nitric acid (5:2:2), and the modified heterocyclic resin glue is etched away with sulfuric acid hydrogen peroxide, and then The surface of the obtained N-type GaN layer is cleaned. The remaining isolation strip 2 is removed, and the P and N electrodes are formed by using a common process to complete the preparation of the semiconductor light emitting device.

In this embodiment, the inclination angle of the side wall of the epitaxial layer is 80°, and the yield rate of chip production is significantly improved.

Embodiment 3 As shown in FIG. 4 a , a buffer layer, an N-type GaN layer, an active layer, and a P-type GaN layer are sequentially grown on a sapphire substrate 100 to form an epitaxial layer 110 . The sapphire substrate 100 is mechanically ground, thinned and polished. As shown in Figure 4b, the epitaxial layer 110 is etched by ICP etching method, the chamber pressure is set to 700mPa, the Cl ₂ , BCl ₃ and Ar gas flow rates are 50 sccm, 10 sccm and 5 sccm respectively, the radio frequency power is 100W, and the ion source power is 600W, etch the epitaxial layer 110 to expose the sapphire substrate 100 to form a plurality of discrete dies 1, and at the same time keep part of the epitaxial layer 110 as the isolation zone 2 between every two adjacent dies 1, different The isolation zone 2 between the tube cores 1 is discontinuous, the width of the isolation zone 2 is 20 microns, and the width of the groove 3 between the edge of the adjacent tube core 1 is 10 microns, and the inclination angle of the side wall of the epitaxial layer after etching is 60°. As shown in FIG. 4 c , glue is coated on the etched epitaxial layer 110 and bonded to the support substrate 120 and cured. The supporting substrate 120 is any one of Si, ceramics, W, Cu, Mo, GaAs, graphite, and glass. As shown in FIG. 4 d , resin glue 210 is coated on the other side of the supporting substrate 120 . The resin glue 210 plays a role in relieving stress during the laser lift-off process. In order to make the coated resin glue 210 flat, as shown in FIG. 4e, use a transparent auxiliary substrate 220 such as glass or sapphire to flatten the resin glue 210, and then use ultraviolet light to cure the resin glue 210, and remove the auxiliary substrate 220. As shown in FIG. 4f, the sapphire substrate 100 is removed by laser lift-off. As shown in FIG. 4g, the resin glue 210 is removed. The remaining isolation strip 2 is removed, and the P and N electrodes are formed by using a common process to complete the preparation of the semiconductor light emitting device.

In this embodiment, the inclination angle of the side wall of the epitaxial layer is 60°, and the yield rate of chip production is slightly improved.

Embodiment 4 As shown in FIG. 5 a , a buffer layer, an N-type GaN layer, an active layer, and a P-type GaN layer are sequentially grown on a sapphire substrate 100 to form an epitaxial layer 110 . The sapphire substrate 100 is mechanically ground, thinned and polished. As shown in Figure 5b, using a 355nm ultraviolet laser, the laser power is 1.2W, the frequency is 120KHz, and the rate is 120mm/s, the epitaxial layer 110 is etched to expose the sapphire substrate 100, forming a plurality of discrete tube cores 1, and simultaneously Part of the epitaxial layer 110 is reserved between every two adjacent tube cores 1 as the isolation zone 2, and the isolation zone 2 between different tube cores 1 is discontinuous, and the width of the isolation zone 2 is 40 microns, which is the same as that of the corresponding tube core 1. The width of the groove 3 between the edges of the adjacent tube core 1 is 10 microns, and the inclination angle of the side wall of the epitaxial layer after etching is 90°. As shown in FIG. 5 c , a high-temperature epoxy resin modified glue is coated on the etched epitaxial layer 110 , bonded to the first temporary substrate 310 and then cured. As shown in FIG. 5 d , the sapphire substrate 100 is removed by using a laser lift-off method, using a 248 nm excimer laser with a power of 550 mW. As shown in FIG. 5 e , after depositing a TiAu protective layer on the peeled surface, it is bonded to the second temporary substrate 320 . As shown in Figure 5f, after protecting the second temporary substrate 320 with wax, the first temporary substrate 310 is etched with hydrofluoric acid plus hydrogen peroxide plus nitric acid (5:2:2), and the high temperature epoxy is etched at 100°C with toluene. Resin modified glue. As shown in FIG. 5g, the exposed epitaxial layer is bonded to a supporting substrate 120, which is a silicon substrate. As shown in Figure 5h, the supporting substrate 120 is protected with wax, the second temporary substrate 320 is etched with hydrofluoric acid plus hydrogen peroxide plus nitric acid (5:2:2), and the modified heterocyclic resin glue is etched away with sulfuric acid hydrogen peroxide, and then The surface of the obtained N-type GaN layer is cleaned. The remaining isolation strip 2 is removed, and the P and N electrodes are formed by using a common process to complete the preparation of the semiconductor light emitting device.

In this embodiment, the inclination angle of the side wall of the epitaxial layer is 90°, and the yield rate of chip production is greatly improved.

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone who is familiar with the technology can easily think of changes or replacements within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

1. A method for preparing a semiconductor light-emitting device, comprising: growing a buffer layer, an N-type GaN layer, an active layer, and a P-type GaN layer sequentially on a sapphire substrate to form an epitaxial layer; etching the epitaxial layer to expose the sapphire substrate The bottom to produce a plurality of discrete tube cores; the etched epitaxial layer is combined with the supporting substrate; the sapphire substrate is removed by laser lift-off method; it is characterized in that the etched epitaxial layer has a side wall inclination angle of 60°-90°. 2. The method for manufacturing a semiconductor light emitting device according to claim 1, characterized in that the inclination angle of the sidewall of the epitaxial layer is 75°-85°. 3. The method for manufacturing a semiconductor light-emitting device according to claim 1, characterized in that the method of combining the etched epitaxial layer with the support substrate is eutectic bonding or glue coating and then curing. 4 . The method for manufacturing a semiconductor light emitting device according to claim 1 , wherein a part of the epitaxial layer is reserved as an isolation zone between the tube cores, and at least one of the isolation zones around the tube cores is not connected. 5. The method for manufacturing a semiconductor light emitting device according to claim 4, characterized in that the width of the groove between the isolation zone and the edge of the adjacent die is 1-100 microns. 6. The method for manufacturing a semiconductor light emitting device according to claim 4, characterized in that the width of the isolation zone is 5-100 microns.

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