Which Type of Lasers Are Used in Semiconductor Manufacturing?

The whole of semiconductor laser technology is more complex than a simple approach to the manufacturing process. This same sentiment applies to laser marking methods, as there is a long list of technologies included with the term.

Laser technology is frequently used in semiconductor manufacturing because of its thin, precise, versatile, and powerful beam. Using lasers for manufacturing is effective and has been successful with cutting, marking, coating removal, measuring, and welding. In this article, we’ll discuss the fundamentals of semiconductor lasers, the types of lasers used, their applications, the manufacturing process, and the future of lasers.

Solid state lasers are the most frequently used lasers for manufacturing. These lasers are a category of lasers known for high power and their use of ores for the laser medium. The ores are commonly made up of yttrium, aluminum, garnet, or yttrium vanadate crystal. The machine oscillates light through the medium in order to refine the wavelength and output a clean, concise beam.

Fiber lasers are a type of laser within the solid-state category. These lasers are known for high-speed marking, engraving, and cutting. A fiber laser uses fiber as a resonator and creates an overlapping structure with fiber cladding doped with Yb ions. After that, it pumps the laser diode excitation inside for use. Some uses for fiber lasers include removing burr in the preproduction process, marking traceability codes, and removing resin to analyze defects. KEYENCE’s fiber laser is called the MD-F Series 3-Axis Fiber Laser.

Excimer lasers are deep ultraviolet lasers with a 126 nm to 351 nm wavelength. These semiconductor lasers are used for polymer micro-processing.

Semiconductors go through a long production process that includes various cutting steps. For instance, semiconductors are made from cutting out wafers from crystal blocks and cutting stencils out of films.

Because of the high-powered laser with a thin beam, lasers are used for the ability to cut cleanly. Clean cuts are necessary as semiconductors have to fit nicely into the final product, like a phone, computer, or camera.

Semiconductor (LD) laser welding, also known as laser diode welding, is the process of melting adjoined sections together. This type of laser welding is special because it does not use a lamp as the excitation source. One example of adjoining in semiconductor manufacturing is welding a wafer to a supporting plate.

Coating removal for semiconductors is part of the manufacturing process for cleaning the semiconductor or analyzing defects. Removing coating could be deburring resin or copper, removing gold plating, or removing thin film coating. In the instance of deburring, semiconductor lasers use their thin and precise beam to remove excess material without damaging any of the product.

On the other hand, removing coating for analyzing a defective mold also allows manufacturers to see a defect without disassembling and damaging the product.

Laser marking machines are used for 2D code marking on IC chips, LED ceramic packaging, silicon wafers, and more. Since the laser marker has an extremely small beam spot, the laser can create readable marks even at microscopic levels.

Laser sensors can measure semiconductors at many different steps of the semiconductor fabrication process. With wafers, KEYENCE’s LT-Series laser sensor measures thickness, wear level, and thermal expansion. Sensors can also measure wire bonding height, the height of resin molds, and the shape of BGA balls.

You can never go too far with safety, and following regulations guarantees manufacturing processes can continue from one day to the next.

Efficient

Lasers use automation and repeated tasks to conduct processing. The only hands-on step involves programming the laser for the application that is needed.

Versatile

Because excimer lasers have high absorption rates and thin beams, laser ablation can be done on a wide range of materials.

Precise

With the power and thin beam combined, excimer lasers are precise when conducting ablation. For instance, KEYENCE’s lasers include 3-axis control that autofocuses and autocorrects based on the target area for uniformity across the whole material.

High Initial Cost

Laser machines are an investment with a high initial cost; however, the benefits of precision and versatility often provide a great ROI.

Wafers are the raw material used for starting fabrication. Lasers have many roles with wafers including, cutting wafers out of an ingot, dicing after lamination, marking identifiers for "good" or "no good", and marking 2D codes.

After the wafers are cut out by lasers, they are bonded to lead frames. For the lead frame to be ready for the wafer, the laser will mark the frame with an identifying mark. After that, laser markers roughen the surface for the lead frame and wafer adhesion. Once they are stuck together, the laser marker removes the burrs. Finally, when the burrs are removed, the laser marker once again marks the frame.

Now that the lead frame is done, it is ready for molding and processing to turn into an IC package. When the IC package is made, the laser once again marks identification on both the wafer and package.