Manufacture of integrated circuits

Today the market for photoresists used in the manufacture of integrated circuits is estimated to be 750 million U.S. aimually, with... 

Chemicals used in the manufacture of integrated circuits (qv) need to be controlled to even mote stringent levels of purity than either USP or ACS grades. 

Atomie and molecular studies of catalysts Chemical processing in the manufacture of integrated circuits Studies of the dynamics of suspensions and microstructured fluids Improving the rate and capacity of separations equipment... 

F. Steps in the Manufacture of Integrated Circuits The fabrication of ICs begins with the preparation of silicon of very high... 

Silicon solar-cells are fabricated using silicon discs in a manner similar to that described previously for manufacture of integrated circuits. The basic external structure used in solar cells is shown in the following diagram ... 

Electronic Materials. Applications of photopolymer technology to electronic products is probably one of the largest imaging categories in terms of sales and total number of patents and publications. A wide variety of products have been developed for the production of printed wiring boards (PWB) and the manufacture of integrated circuits (IC). 

It may be considered a fortunate coincidence that this book is published at the time of the introduction of copper interconnection technology in the microelectronics industry. In 1998 the major electronic manufacturers of integrated circuits (ICs) are switching from aluminum conductors produced by physical methods (evaporation) to copper conductors manufactured by electrochemical methods (electrodeposition). This revolutionary change from physical to electrochemical techniques in the production of microconductors on silicon is bound to generate an increased interest and an urgent need for familiarity with the fundamentals of electrochemical deposition. This book should be of great help in this crucial time. 

The nonuniformity in CMP is sometimes confusing because there are three different thickness specifications pre- and post-thickness and thickness delta. To describe the CMP tool performance, and for the daily tool qualification, usually the nonuniformity of delta thickness is used. However, for quality control of the manufacturing of integrated circuits, the nonuniformity for the final thickness is used. The relation between the delta and the final thickness nonuniformities is explained as in the Fig. 12. 

Silicon dioxide films have been an essential factor in the manufacture of integrated circuits from the earliest days of the industry. They have been used as a final passivation film to protect against scratches and to getter mobile ion impurities (when doped with phosphorus). Another application has been as an interlayer dielectric between the gate polysilicon and the aluminum metal-ization. Initially, most such films were deposited in atmospheric pressure systems. In recent years, low pressure processes have assumed greater importance. We will begin by examining the atmospheric process. 

Up to this point, we have been considering PECVD films that are being used commercially in the manufacture of integrated circuits. We will now consider PECVD of other films that may find practical application in the future. At the present time, they are still considered experimental. 

Baekeland succeeded where others had failed, not only because he carried out his process under pressure but also because he recognized the importance of controlling the relative proportions of phenol and formaldehyde. Too little formaldehyde, for example, and the product was weak and brittle. Baekeland also worked out conditions for reacting phenol with a small amount of formaldehyde under acidic conditions, to produce a thermoplastic material he called novolac. Novolac can be converted into a thermoset similar to Bakelite by heating with additional formaldehyde. Novolac became useful as a positiveworking photoresist for the manufacture of integrated circuits some 60 or 70 years later. We will discuss photoresists later in this chapter. 

Silicon was discovered by Berzelius in 1824. Although knowledge of the element itself is fairly recent, compounds of silicon have been known for thousands of years. For example, pottery, brick, ceramics, and glass are made of silicates that are naturally occurring materials. In addition to these uses of silicates, highly purified elemental silicon is used in the manufacture of integrated circuits or chips that are used in the electronics industry. It is also alloyed with iron to make Duriron (Fe, 84.3% Si, 14.5% Mn, 0.35% and C, 0.85%), an alloy that resists attack by acids. This alloy is used in the manufacture of drainpipes and the cores of electric motors. 

To avoid reaction between the Si substrate and A1 metallizations during the manufacture of integrated circuits at high temperatures, diffusion barriers are necessary. It has been demonstrated that high crystallization-temperature glasses such as Ta Ir glasses make excellent diffusion barriers in many microelectronics applications. 

The chemical modification of surfaces and films i essential in the manufacture of integrated circuits. Patterns and material must be transferred to substrate surfaces and removed from them. As the dimensions of advanced electronic devices shrink to the submicron and molecular scale, properties of the processing techniques become increasingly critical. Characteristics such as low temperatures, low levels of induced dam. ge and contamination, and molecular scale selectivity and controllabilit] are essential. The use of radiation-induced chemistry is desirable if it can be conducted at lower temperatures and with smaller levels of damage and contamination than particle impact and thermal methods. 

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