Wafer handling

Raw throughput improvement can be achieved by reducing the amount of material that must be polished away, increasing film removal rates, and increasing the wafer-handling efficiency. Wafer-handling efficiency is addressed in the following sections. 

Obviously, defects can be seen with an optical microscope. What is needed is a quick way to count different types of defects on each wafer processed. For this purpose, a commercial computerized unit has been developed that can distinguish between point, tine and area defects. The measurement and wafer-handling unit is shown in Figure 13. 

There are a large number of potential sources for particles to fall onto a wafer. Advanced tool design and proper selection of clean room technology can be very effective in reducing or eliminating this type of defect. In addition, it is desirable to eliminate manual intervention. The use of minienvironment around the tools and closed wafer-handling cassettes such as FOUP (front opening unified pod) are proven effective. These types of particles are more frequently seen in small clean rooms where wafers are handled manually. 

A larger part of the wafer handling occurs in an ultra clean environment. Therefore there are less transfers between vacuum and atmosphere. This should reduce particle contamination problems and lead to less defects. 

PEP CHIP. A microscc lc particle on a silicon wafer was fingerprinted as a piece of polyethylene terephthalate. ihe source of this contaminant was identified as a wafer handling basket. This result was especially surprising because these baskets had been "guaranteed not to chip and produce debris. 

BOE followed by in-situ replacement with water and then with various intermediate liquids, ending with cyclohexane [17]. This chemical has a melting point around -5 °C and its vapor has a high partial pressure. The wafer immersed in liquid is transferred to a vacuum chamber. Upon evacuation of the chamber, the liquid solidifies and is subsequently sublimated. Processing issues are wafer handling and throughput. 

Fig. 15.2. A 300 mm high current implanter showing (left to right) gas delivery system, ion source, analyzer magnet, process chamber, and wafer handling system...

Fig. 6.11-9 a) Complex near-net or net shape parts for wafer handling and processing, b) 1C (integrated circuits) handling and testing and other semiconductor manufacturing made ofVespel polyimide non-melt processable compound (courtesy, DuPont, Newark, DE, USA)... 

In the old days when wafers were handled with tweezers, before the advent of the automated wafer-handling systems of today, novolac resists were notorious for their particle generation problem, which eventually led to the introduction of automated wafer handling systems. " ... 

I. Mori, K. Sugihara, C. Itoh, M. Tabata, and T. Schinozaki, An electron beam image projection system with automatic wafer handling, Microelectron. Eng. 3, 69 (1985) T.W. O Keefe, J. Vine, and R.M. Handy, An electron imaging system for the fabrication of integrated circuits, Solid... 

From its onset, the semiconductor industry has relied on fluoropolymers as the material of construction for wet processing equipment, fluid transport systems, and wafer handling tools. Semiconductor manufacturing processes are extremely intolerant of particulate and chemical contamination which can, even in trace amounts, cause severe decreases in yields. Therefore, fluoropolymers purity and resistance to chemical attack have created an important role for plastics in the semicon industry. In the next section, we briefly review the chip manufacturing industry to provide the reader with a more in-depth understanding of the important role that fluoroplastics play in this industry. 

Microcracks at wafer handling or supporting zones are becoming a topic of great importance to overall process yield. The high speeds of wafer handling robots require a firm grip on the wafer by vacuum or mechanical clamps, and... 

In 2006 GE announced a new amorphous TPI, Extern , with Tg < 311°C, and high strength, stiffness, chemical and creep resistance at T < 230°C.The new TPI finds applications in auto, aerospace and military products, downhole oil and gas production, medical membranes, electrical connectors, electronics for lead-free soldering, semiconductor wafer handling, and specialty films for insulators and flexible circuitry. 

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