1. Challenges Faced by Traditional Die-Cutting Technology With the trend towards thinner and smaller ICs, packaging has undergone significant changes. For example, memory ICs have evolved from single-chip packaging to multi-layer chip stacks, with 7 or 8 layers of chips stacked within a single IC. Samsung Semiconductor in South Korea even publicly demonstrated its ultra-thin wafer packaging technology with a 16-layer stack earlier this year, achieving a packaged size smaller than the original IC of the same capacity. Consequently, chip thickness has decreased from 650μm to 120, 100, 75, 50, 25, and 20 μm. When the thickness drops below 100 μm, traditional die-cutting technology has encountered problems, with production capacity declining and breakage rates rising sharply. At this stage, chips are highly valuable, and a breakage rate of a few percentage points can wipe out the profits painstakingly generated by the factory. Furthermore, in wafer manufacturing technology, low-k materials are used to improve efficiency, and their structures contain multiple layers of metal and some fragile materials. When traditional diamond cutting tools encounter highly ductile metal layers, the diamond particles are easily encased in the metal, losing some of their cutting ability. In this situation, cutting can easily result in chip breakage or tool breakage. In fact, besides advanced ICs, diamond cutting tools also have many limitations in the dicing of traditional diode wafers: for example, in GPP wafer dicing, mechanical grinding causes severe damage to the glass coating layer, leading to poor insulation and serious leakage. To overcome this problem, the industry has had to develop various complex processes to compensate for this deficiency. One method involves growing the glass layer only along the cutting street. This method has been used for square dies for many years. However, for hexagonal dies, there is a problem: the triangles on each side of the hexagon are wasted. In the diode industry, where every millimeter counts, a loss of 30% to 40% of the main raw material (chip) is extremely serious. With new technologies, this long-standing loss can be completely stopped. The dicing of high-brightness LED wafers with sapphire substrates also presents serious dicing problems. Traditional sapphire wafer dicing primarily involves two methods: using a diamond pen or a diamond blade. A very shallow line is first drawn on the sapphire wafer before dicing. Because sapphire itself is extremely hard, tool wear is very severe regardless of the method chosen; the overall yield after dicing is also low. These long-standing problems plaguing the LED industry have now been greatly improved with the application of ultraviolet laser dicing systems. In the field of microelectromechanical systems (MEMS), an increasing number of chips require drilling, irregular hole opening, and local thinning. The cutting of composite chips bonded to glass and silicon, chips coated with diamond layers, and chips with complex microstructures are all beyond the capabilities of diamond blades. However, the market demand for these products continues to grow, forcing the industry to seek next-generation dicing solutions. 2. The Rise of Laser Dicing Laser dicing has been used for many years, primarily with 1064 nm Nd:YAG as the light source. While its quality was acceptable in some low-end applications, it was never widely accepted in integrated circuit processing due to its large heat-affected zone, severe contamination, and significant thermal deformation. In recent years, ultraviolet laser technology has matured, offering significantly improved cutting quality compared to 1064 nm laser sources. Its advantages are particularly evident in sapphire wafer dicing, making it a mainstream solution in the industry. Among various laser solutions, the most unique and little-known is the Swiss micro-waterjet laser technology, a world-patented technology. This technology excels in many aspects, especially in eliminating the heat-affected zone. Micro-waterjet laser dicing technology has gained recognition and adoption from major global semiconductor packaging manufacturers, particularly for dicing ultra-thin wafers, low-k wafers, diamond-coated wafers, diode glass-passivated wafers, microelectromechanical chips, composite wafers, and irregularly shaped dies, demonstrating remarkable performance. 3. Micro Waterjet Laser Technology 3.1 Technical Principles The millennia-old concept of "water and fire being incompatible" was overturned in 1993 by the distinguished Swiss scientist Dr. Bernold Richerzhagen. He ingeniously combined the advantages of waterjet technology and laser technology to create the micro waterjet laser (or more accurately, waterjet-guided laser). He focused the laser beam and guided it into a micro-water column thinner than a human hair, thereby guiding the beam and cooling the workpiece, eliminating the excessively large heat-affected zone of traditional lasers. This significantly improves the quality of laser cutting, making it ideal for high-precision, high-cleanliness processing in semiconductors, medical devices, electronics, aerospace, and other industries. As shown in Figure 1, the laser beam is introduced from above, passes through the focusing lens and the window of the water chamber, and focuses at the center of the nozzle. [align=center]Figure 1. Micro-waterjet laser principle[/align] Low-pressure pure water enters from the left side of the water chamber and is ejected through micro-holes in the diamond nozzle. Due to the nozzle's fluid dynamics design, the resulting water column is both straight and round, like an optical fiber. The diameter of the water column varies depending on the nozzle orifice, generally thinner than a human hair, with various specifications ranging from 100 to 30 μm. The laser is guided to the center of the water column, and utilizing the principle of total internal reflection at the interface between the micro-water column and air, the laser travels along the water column. Processing can be performed within the range where the water column remains stable and does not burst. The effective working distance is typically 1000 times the nozzle orifice diameter. For example, if the nozzle is 100 μm, its effective working distance is 100 mm. This is unattainable by traditional lasers, as traditional lasers can only process at the focal point. Different wavelengths can be selected for the laser source, as long as the energy of that wavelength is not absorbed by the water. Commonly used wavelengths for precision machining are 1064–355 nm. Furthermore, lasers used for micromachining are almost all pulsed lasers. Traditional lasers, whether pulsed or continuous, always leave energy residue on the cutting path. This energy accumulation and conduction are the main causes of thermal damage and burns around the cutting path. Microwaterjet lasers, however, use a water jet to quickly remove the residual heat from each pulse, preventing it from accumulating on the workpiece, resulting in a clean and sharp cutting path. The heat-affected zone (HAZ) problem is significantly reduced. Therefore, Laser MicroJet technology is suitable for high-precision applications such as semiconductors. 3.2 Features Compared to traditional lasers, microwaterjet lasers have many significant advantages. For example, they have no heat-affected zone, completely preventing workpiece burns, and producing clean, sharp cutting paths free of slag, burrs, thermal stress, mechanical stress, and contamination. This makes them ideal for cutting and processing high-precision devices in semiconductors, electronics, medical, and aerospace industries. Micro waterjet lasers are suitable for a wide range of materials, from metals to their alloys, such as stainless steel, titanium, molybdenum, magnesium, nickel, copper, and Invar, as well as semiconductor materials like silicon, germanium, and gallium arsenide (GaAs), and even silicon carbide (SiC), CBN, diamond, ceramics, and rubber—a true all-rounder. It can even cut rubber and stainless steel sheets simultaneously without burning the rubber layer, something completely impossible with traditional lasers. This technology can be used for cutting, drilling, grooving, printing, surface heat treatment, and many other extremely fine and complex shape processing applications. Ultra-thin silicon wafers are 5 to 10 times faster than traditional diamond cutters and can cut any shape, offering unparalleled functionality. In semiconductor chip cutting applications, it breaks through the long-standing limitation of chip dicing being restricted to straight lines. Designers can now unleash their creativity without constraints. Figures 2 and 3 clearly show the difference caused by the size of the heat-affected zone (HAZ) in the two stainless steel cutting photographs. Traditional lasers, due to their large HAZ, cannot perform micro-cutting, greatly limiting their application areas. [align=center]Figure 2 Stainless steel sheet with severe heat transfer during traditional laser cutting Figure 3 Stainless steel sheet micro waterjet laser cutting[/align] Micro waterjet laser cutting, with its excellent heat-dissipating cutting technology, has greatly expanded the field of precision micromachining, giving rise to many new products and processes. 4 Dicing problems of low dielectric constant materials and ultra-thin wafers Ultra-thin wafers, originally used only for high-end products, are becoming increasingly common and thinner. Processing ultra-thin wafers is not only a problem of the thickness of the silicon substrate itself, but also becomes more complex with the addition of many hard, brittle, and highly ductile metal pads. Even if the diamond blade carefully cuts through the silicon substrate, metal debris may adhere to the diamond particles, greatly reducing cutting ability. Maintaining the feed rate at this point will inevitably result in wafer breakage and blade breakage. Major dicing machine manufacturers, such as Disco and TSK, have all switched to lasers, indicating that mechanical methods have reached an insurmountable predicament. Unfortunately, lasers also have their own problems. Here, the characteristics of diamond saw blades, traditional lasers, and micro waterjet lasers are discussed: 4.1 Diamond Saw Blade It easily causes chipping or cracking on the wafer surface. It is prone to breakage and fragmentation when encountering metal layers, resulting in slow cutting speed and a high fragmentation rate. However, it produces a smooth cut surface and easy depth control when cutting silicon substrates. When using DAF (Die Attach Film), it can cut through the DAF without damaging the Blue Tape. 4.2 Traditional Laser Traditional lasers, also known as dry lasers, are limited to low-end chips, such as solar cells, due to unresolved heat-affected zone issues. While using a 3x frequency multiplier improves this, it can only perform scribe lines. Cutting through the surface will still burn the chip, DAF, and Blue Tape. 4.3 Micro Waterjet Laser It can easily remove surface material and silicon substrate from the cutting path. When cutting ultra-thin wafers (50 μm), its speed is several times faster than a diamond saw. The disadvantages are that, like dry lasers, it can burn out the DAF, and the cut surface is not as smooth as mechanical grinding. From the above, it's clear that each has its advantages and disadvantages. 4.4 Solution Since there is no perfect solution, we have to settle for less. For Diamond Saw, the difficulty lies in the surface material of the wafer. For micro waterjet lasers, the headache is the potential to burn out the DAF. Therefore, combining the advantages of each and processing it in two steps would be satisfactory. First, use a micro waterjet laser to make a shallow cut, a process called grooving, to remove all material from the cutting path, whether metal or brittle. The micro waterjet laser can use a nozzle the same width as the cutting path, like a bulldozer, to remove all the troublesome material on the surface, exposing the Silicon Substrate. Then, use the Diamond Saw to cut through the silicon substrate and DAF, stopping precisely on the Blue Tape surface. Because grooving can only remove a depth of tens of micrometers on the surface, micro waterjet lasers can operate at a high speed of 250 mm/s. From a production line balance perspective, a single micro waterjet laser system requires at least five Diamond Saw machines to operate effectively. From an equipment investment perspective, this seems to be the most efficient approach. Not only will new equipment not render old machines idle, but it will also increase production capacity, truly complementing each other. Micro waterjet lasers can also perform tasks that diamond tools cannot, such as cutting irregularly shaped grains and drilling through-holes or blind holes, as shown in Figures 4 and 5. [align=center] Figure 4: Silicon wafer laser drilling Figure 5: Larger microscope image, 100 micrometer aperture[/align] 5. Semiconductor Wafer Dicing Series from Swiss company Sinopharm The entire series is equipped with high-precision linear guides and CNC control, a TFT LCD touchscreen and advanced human-machine interface software, a CCD camera, automatic vision aiming, and remote communication diagnostics. It can cut any shape of grain, such as hexagons, circles, and irregular shapes. 5.1 Equipment Introduction (1) LDS 200A/LDS:300A. LDS 200A/LDS:300A - Fully automatic 200 mm/300 mm silicon wafer waterjet laser cutting system, Cassette to Cassette, automatic vision system alignment, cutting, cleaning, and material feeding and unloading are completed in one go. Suitable for continuous mass production. The performance of ultra-thin silicon wafer cutting is several times faster than the traditional diamond knife cutting method. (2) LDS 200C. LDS 200C - Automatic 200 mm silicon wafer waterjet laser cutting system, manual or vision system automatic aiming, cutting, automatic cleaning with ultrapure water after cutting, manual material feeding and unloading, suitable for mass production. (3) LDS 200M. LDS 200M - Manual 200 mm silicon wafer waterjet laser cutting system, manual material feeding and unloading, manual or vision system automatic alignment. Cutting, suitable for research and development or small-batch and diverse production applications. (4) LGS 200. The LGS 200 is a 200 mm Cassette to Cassette waterjet laser fully automated silicon wafer trimming system, particularly suitable for trimming the outer diameter of ultra-thin silicon wafers, significantly reducing the breakage rate of ultra-thin wafers. It can also be used for hole drilling, slotting, and free-shape chip dicing. 5.2 Synova, a company soon to be launching a hybrid system, has also announced a collaboration with a subsidiary of the renowned Diamond Saw company DISCO to develop a hybrid system combining diamond cutting tools and micro-waterjet lasers. This hybrid system will set a new milestone in wafer dicing technology. The system combines the advantages of both technologies and takes into account the problems arising from new semiconductor wafer materials and future trends, and is expected to solve the current challenges in dicing within the semiconductor industry. Let's wait and see. 6 Conclusion Although more and more people are paying attention to micro-waterjet laser technology, it is undeniable that most people are still unfamiliar with it. Although many applications have been developed both domestically and internationally, there is actually a much larger market yet to be explored. If we can re-examine and rethink the existing production processes in various industries, are there any processes that are unsatisfactory? Are there any difficult problems that companies cannot solve? Are there any materials that cannot be cut or cut poorly? Are there any things that we thought lasers could do but were disappointed after trying them? We believe that these questions contain business opportunities. The existence of problems is what makes solutions valuable.