Protection of integrated circuits

Levinson, Principles of Lithography, 2nd ed., SPIE Press, Bellingham, WA, p. 262 (2005). Hershel, Pellicle protection of integrated circuit (IC) masks, Proc. SPIE 275, 23 28 (1981). 

Figure 7.3. The evolution of electronics a vacuum tube, a discrete transistor in its protective package, and a 150 nun (diameter) silicon wafer patterned w ith hundreds of integrated circuit chips. Each chip, about I enr in area, contains over one million transistors, 0..35 pm in size (courtesy M.L. Green, Bell Laboratories/Lucent Technologies).

The present chapter deals with the CVD of metals and some metal alloys and intermetallics. The metals are listed alphabetically. The range of applications is extensive as many of these materials play an important part in the fabrication of integrated circuits and other semiconductor devices in optoelectronic and optical applications, in corrosion protection, and in the design of structural parts. These applications are reviewed in greater depth in Chs. 13 to 19. 

A variation of this technique can be used for the preparation of integrated circuits with a resolution of the order of the jum. In this case a silicon wafer is protected by the resist which must be deposited with an accurately controlled thickness. Exposure to light is done through a mask (with an optical reduction of the size of the image). 

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. 

The most important of these iprs conventions include the Paris Convention for the Protection of Industrial Property (1967) the Berne Convention for the Protection of Literary and Artistic Works (1971) the Rome Convention (1961) and the Washington Treaty on ip in Respect of Integrated Circuits (1989). UPOV, initiated by a group of western European countries, is based on the International Convention for the Protection of New Varieties of Plants signed in Paris in 1961. 

In the processing of integrated circuits, silicon dioxide (SiOa) can be used as a mask during ion implantation or diffusion of impurity into silicon, for passivation, for protection of the device surface, as interlayers for multilevel metallization, or as the active insulating material — the gate oxide film in metal-oxide-semiconductor (MOS) devices [1, 2], At the present time, several methods have been developed for the formation of Si02 layers, including thermal and chemical oxidation, anodization in electrolyte solutions, and various chemical vapor deposition (CVD) techniques [2, 3],... 

Die passivation layers were first introduced to protect the metallisation of integrated circuits from mechanical damage during assembly. However, it soon became apparent that the passivation layer was a crucial factor in determining the failure rate in moist ambients. Originally, pure chemical vapour deposition (CVD) silicon dioxide was used, but later phosphorus was added to relieve strain in the layer and thus prevent cracking and loss of adhesion. There is also interest in, and limited use of, other forms of passivation such as silicon nitride, oxynitride and polyimide. 

Multilayered structures play an important role in the production of, e.g., biomaterials, catalysts, corrosion protectors, detectors/diodes, gas and humidity sensors, integral circuits, optical parts, solar cells, and wear protection materials. One of the most sophisticated developments is a head-up-display (HUD) for cars, consisting of a polycarbonate substrate and a series of the layers Cr (25 nm), A1 (150 nm), SiO, (55 nm), TiO, (31 nm), and SiO, (8 nm). Such systems should be characterized by non-destructive analytical methods. 

What are the technologies of the integrated circuits that are being used within the design of the system One cannot protect something, if one doesn t know how it breaks. 

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