Anshan Heli Laser Equipment Co., Ltd.
National Service Hotline : 400-641-6888
Address: No. 368 Qianshan Road, High-tech Zone, Anshan City
Dongguan Heli Laser Equipment Co., Ltd.
Address: No. 48 Wenxiang Road, Xiaoxiang, Wanjiang District, Dongguan City, Guangdong Province
Contact: Mr. Yang
The semiconductor manufacturing industry is developing rapidly, and "green" technology undoubtedly has a bright future. This requires new laser processing processes and technologies to achieve higher production quality, yield and yield. In addition to the continuous development of laser systems, new processing technologies and applications, improvements in beam transmission and optical systems, and new research on the interaction between laser beams and materials are all necessary to keep green technological innovations moving forward. The following sections focus on the processing and application of UV DPSS lasers, excimer lasers, and fiber lasers in the semiconductor industry.
Application of UV DPSS Laser in LED Wafer Dicing
Ultraviolet diode pumped solid state (DPSS) laser system has the characteristics of high reliability and good process repeatability. It is widely used in micro-processing, surface treatment and material processing. This UVDPSS laser processing method is superior to other laser processing methods or mechanical and chemical processing methods, and has great development potential in semiconductor and other industrial applications.
DPSS lasers are widely used in micromachining fields such as dicing, cutting, structural construction, via drilling, etc. to process the following materials: silicon wafers, sapphire, CVD CVD diamond, III-V semiconductors (arsenic crops, phosphating Indium, potassium phosphide) and group III nitrides (nitride, aluminum nitride), etc. DPSS lasers are also used for micromachining of ceramic, plastic and metal materials.
355nm and 266nm multi-frequency DPSS lasers can output lasers with a power of several watts, a high repetition rate in the order of kHz, and high pulse energy in the UV band. Short-pulsed beams can produce extremely high power density after being focused. The film can quickly vaporize the material. In the usual laser scribing process, a simple technique of far-field imaging is used to focus the beam to a small point and then move it to the wafer material. Different materials require different light intensities due to their different characteristics of absorbing light, but this kind of focus spot for far-field imaging is not flexible enough to adjust the optimized light intensity. Too strong or too weak light will affect laser scribing effect. And the usual laser scribing is limited to obtain the smallest focused spot, which determines the resolution of the scribing.
To achieve the ideal processing effect, it is important to optimize the laser light intensity. Therefore, a new laser scribing method is needed to overcome the defects of the existing technology. The technical staff of the United States JPSA company has developed an effective beam shaping and transmission optical system. This system can obtain a very narrow 2.5 micron notch width. It can adjust and optimize the laser intensity while ensuring the minimum focused spot, which greatly improves the semiconductor crystal. The speed of circular slicing, while reducing the degree of excessive heating and collateral damage to the material. This new laser processing technology and technology can achieve higher production quality, higher yield and output.
Figure 1.Laser scribe for GaN-Sapphire wafers with a slit width of 2.5 microns
JPSA develops lasers with different wavelengths, making them particularly suitable for wafer cutting applications. The 266nm DPSS laser is used to scribble the gallium nitride front side of blue LED sapphire wafers. The tangential scribe speed can reach 150mm / s. Approximately 15 wafers can be processed in one hour (standard 2-inch wafer, die size 350m × 350m), but the notch is small (less than 3m). The laser process has the characteristics of high productivity and small impact on the performance of the LED, and allows deformation and bending of the wafer. The cutting speed is much higher than that of the traditional mechanical cutting method.
In addition to sapphire, silicon carbide can also be used as an epitaxial growth substrate for blue LED wafers. 266nm and 355nm UV DPSS lasers (with a band gap energy of 4.6eV and 3.5eV respectively) can be used for dicing silicon carbide (with a bandgap energy of 2.8eV). JPSA has continued to develop new technologies such as laser absorption enhancement for back-cut dicing, and has developed a double-sided scribe function. The 355nm DPSS laser can perform back-cut dicing from the sapphire surface of LEDs, achieving a dicing speed of up to 150mm / s High-yield back cut dicing, no debris and no damage to the epitaxial layer. For III-V main group semiconductors, such as gallium arsenide (GaAs), gallium phosphide (GaP), and indium phosphide (InP), the typical notch depth is 40m, and the dicing speed of 250 micron thick wafers is up to 300mm / s.
Application of excimer laser in 2D pattern forming and 3D micromachining, LED stripping
The excimer laser industrial processing system has short wavelengths (351, 308, 248, 193, and 157nm, etc.), high power (50 to 100 watts), high energy, large spot area, and uniform spot distribution. Therefore, excimer lasers are suitable for applications such as large-area pattern processing, 3D micromachining, MEMS micromachining, ultraviolet laser lithography, TFT flat laser annealing, and LED laser peeling.
2D pattern forming and 3D micromachining excimer lasers can produce large-area square or rectangular light spots, which are particularly suitable for large-area pattern forming processes and 3D micromachining. An excimer laser can efficiently process materials in a relatively large focusing plane range. For example, a 500 mJ UV beam has a spot area of 7 × 7 mm at an energy density of 1 J / cm 2. Large-area excimer laser beams can be projected onto lithographic masks to micromachine special shapes and patterns; these are called near-field imaging. Through the coordinated movement of the mask and the processed workpiece, larger complex patterns can be obtained by micromachining.
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