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8 III-Nitride LED Chip Fabrication Techniques
Fig. 8.1 Schematic diagram
of a lateral structure
GaN-based LED chip
called a lateral structure LED. The III-nitride LED structure includes a sapphire
substrate layer, an n-type doped layer (n-GaN), a multiple quantum well (MQW)
light-emitting layer, a p-type doped layer (p-GaN), an indium tin oxide (ITO) transparent conductive layer, and metal contacts. In the manufacturing process of the
lateral structure LED chip, an ohmic contact metal is deposited on the surface of
the p-GaN epitaxial layer to form a p-type electrode. The part of the p-GaN and the
multiple quantum well MQW are etched by the ICP process until the n-GaN material
is exposed. Then metal contacts are deposited on n-GaN. Figure 8.1 is a schematic
diagram of a typical lateral structure LED chip. The chip fabrication process of the
lateral structure LED design mainly includes a photolithography process, an etching
process, metal evaporation, and sputtering.
The fabrication processes for LED chips mainly include photolithography, etching
process, thin film deposition, rapid thermal annealing, grinding and polishing
processes. In this chapter, the main basic single-step process mentioned above is
introduced, and the problems that need to be addressed in the processing of LED
chip are given. The main ohmic contact problem among III-nitride LEDs is also
discussed.
8.2 Photolithography
Lithography (Photolithography) is a technique used to remove the area of materials particular defined on the wafer. The essence is to copy the pattern made on the
photomask onto the wafer to be etched later. The principle is similar to that of photography, except that the semiconductor wafer and the photoresist replace the photographic film and the photosensitive coating. Lithography is a temporary graphics
transfer process. The lithography or etching is used as a photomask to complete
the permanent transfer of the pattern. Lithography is one of the most important
process steps in LED fabrication. The photomasks and photoresists are the core of
8 III-Nitride LED Chip Fabrication Techniques
Fig. 8.1 Schematic diagram
of a lateral structure
GaN-based LED chip
called a lateral structure LED. The III-nitride LED structure includes a sapphire
substrate layer, an n-type doped layer (n-GaN), a multiple quantum well (MQW)
light-emitting layer, a p-type doped layer (p-GaN), an indium tin oxide (ITO) transparent conductive layer, and metal contacts. In the manufacturing process of the
lateral structure LED chip, an ohmic contact metal is deposited on the surface of
the p-GaN epitaxial layer to form a p-type electrode. The part of the p-GaN and the
multiple quantum well MQW are etched by the ICP process until the n-GaN material
is exposed. Then metal contacts are deposited on n-GaN. Figure 8.1 is a schematic
diagram of a typical lateral structure LED chip. The chip fabrication process of the
lateral structure LED design mainly includes a photolithography process, an etching
process, metal evaporation, and sputtering.
The fabrication processes for LED chips mainly include photolithography, etching
process, thin film deposition, rapid thermal annealing, grinding and polishing
processes. In this chapter, the main basic single-step process mentioned above is
introduced, and the problems that need to be addressed in the processing of LED
chip are given. The main ohmic contact problem among III-nitride LEDs is also
discussed.
8.2 Photolithography
Lithography (Photolithography) is a technique used to remove the area of materials particular defined on the wafer. The essence is to copy the pattern made on the
photomask onto the wafer to be etched later. The principle is similar to that of photography, except that the semiconductor wafer and the photoresist replace the photographic film and the photosensitive coating. Lithography is a temporary graphics
transfer process. The lithography or etching is used as a photomask to complete
the permanent transfer of the pattern. Lithography is one of the most important
process steps in LED fabrication. The photomasks and photoresists are the core of