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Large-area and low-power laser stripping method for GaN-base epitaxial layer

A laser lift-off and epitaxial layer technology, applied in lasers, semiconductor lasers, laser welding equipment, etc., can solve problems such as poor electrical and thermal conductivity of sapphire hardness, limited crystal quality of GaN-based materials, and complex material growth processes, etc., to ensure integrity Uniformity, reduced energy density requirements, and the effect of relaxing the spot size

Active Publication Date: 2006-05-31
SINO NITRIDE SEMICON
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Problems solved by technology

Due to high thermal stability and relatively cheap price, most GaN-based epitaxial films are mainly grown on sapphire substrates. Difficulty, while heterogeneous substrates also limit the crystal quality of GaN-based materials
In addition to the large-mismatch substrate heteroepitaxial growth technology, the use of mechanical, chemical or laser irradiation methods to peel off the thick GaN film from the substrate has also been developed to obtain a self-supporting GaN bulk material as the substrate. Finally, the homoepitaxial growth technology of the device structure on the GaN thick layer with low defect density has great development potential in improving the growth quality of GaN-based epitaxial materials and improving the overall performance of the device, but this requires prior epitaxial growth on a sapphire substrate. The epitaxy of layered GaN and secondary device structures makes the material growth process complex and expensive

Method used

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  • Large-area and low-power laser stripping method for GaN-base epitaxial layer
  • Large-area and low-power laser stripping method for GaN-base epitaxial layer
  • Large-area and low-power laser stripping method for GaN-base epitaxial layer

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] The technical scheme of embodiment one:

[0034] 1. Adhere the P side of the GaN-based epitaxial wafer on the sapphire substrate to the support substrate such as glass, Si, Cu, etc. with epoxy resin, and place it in a vacuum chamber to remove the air bubbles in the glue to ensure that the epitaxial wafer and the support substrate are stable. Indicates uniform intimate contact without voids.

[0035] 2. Adjust the optical path of the excimer laser, such as figure 1 As shown, two beams are irradiated at the same time. The laser pulse 6 is divided into two beams by the beam splitter 7. The beam 1 is the focused beam obtained by passing the beam split by the beam splitter 7 through the focusing lens 9. The beam is caused by the decomposition of GaN at the interface. the main reason. The other beam is the bias beam, which is obtained by passing the light split by the beam splitter 7 through the reflector 8. The bias beam 2 has a larger spot and a smaller energy density, an...

Embodiment 2

[0039] The technical scheme of embodiment two:

[0040] 1. Adhere the P side of the GaN-based epitaxial wafer on the sapphire substrate to the support substrate such as glass, Si, Cu, etc. with epoxy resin, and place it in a vacuum chamber to remove the air bubbles in the glue to ensure that the epitaxial wafer and the support substrate are stable. Indicates uniform intimate contact without voids.

[0041] 2. Heat the sample with an electric heater 5 or local infrared heating of the sample environment, with a temperature range of 0-300°C

[0042] 3. Irradiating the heated sample with an excimer pulsed laser with sufficient energy density, and performing laser lift-off to separate the GaN epitaxial layer 11 from the sapphire substrate 12 .

[0043] 4. The sample stage adopts a spiral or arc stepping method during laser peeling, such as figure 2 . The angle of the helix is ​​0-360°.

[0044] 5. After the laser scans the sample 10, first soak the sample with hot water higher...

Embodiment 3

[0046] The technical scheme of embodiment three:

[0047] 1. First prepare a large-area P-type ohmic contact electrode directly on the GaN-based epitaxial layer 11 on the sapphire substrate 12, such as vapor-depositing Ni / Au transparent electrode 1, and then alloy it at 500 ° C under oxygen: nitrogen = 1: 1 5 minutes. For epitaxial wafers with LED structures, a reflective layer of Ti / Ag / Ti / Au needs to be added, as shown in Figure 3a. Among them, " / " is the separation symbol between metal layers, such as Ni / Au means two layers of metal, the first layer is metal Ni, the second layer is metal Au, Ti / Ag / Ti / Au means multi-layer metal film, in turn They are metal Ti, Ag, Ti, Au respectively.

[0048] 2. Prepare Ti / Al / Ti / Au ohmic contact electrodes 4 on the upper and lower surfaces of the cleaned n-type highly doped Si substrate 3, as shown in FIG. 3b.

[0049] 3. On the ohmic contact electrode 4 of GaN ohmic contact electrode 1 and Si substrate 3 sides, sputter metal Ni barrier l...

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Abstract

A method for stripping large-area GaN-based epitaxial layer by low-power laser features that the pulse laser beam is used to scan the GaN-loased epitaxial film grown on the sapphire substrate from outside to inside while the sapphire substrate is heated and the laser threshold is biased.

Description

technical field [0001] The invention relates to the field of optoelectronic devices, in particular to a large-area laser lift-off method for a GaN-based epitaxial layer. The present invention proposes a method and technology for achieving large-area uniform, complete, and low-power laser stripping of GaN-based epitaxial layers grown on sapphire, which can obtain large-area, complete GaN-based epitaxial films without sapphire growth substrates, suitable for For devices and materials prepared from GaN-based materials grown on transparent substrates such as sapphire, it is especially suitable for large-area complete and uniform laser lift-off of thinner nitride epitaxial layers. Background technique [0002] GaN-based III-V nitrides are important direct-bandgap wide-bandgap semiconductor materials. Due to its unique bandgap range, excellent optical and electrical properties, excellent mechanical and chemical properties of materials, it can be used in blue, green, purple, ultra...

Claims

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Application Information

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IPC IPC(8): H01L21/00B23K26/402H01L31/18H01S5/00
CPCY02P70/50
Inventor 张国义康香宁陈志忠陈皓明秦志新于彤军胡晓东章蓓杨志坚
Owner SINO NITRIDE SEMICON
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