Tools cluster

Fig. 2. Vacuum processing chamber configuration (a) batch coater (b) load-lock coater (c) in-line coater (d) cluster tool (e) roU coater (batch) and (f) roU coater (air-to-air), [[ccsq]] represents the isolation valve with transfer tooling [[artl]], the motion of fixturing and [[art2]], the access door.

An important recent trend is the tendency for the two processes, CVD andPVD, to merge. For instance, CVD now makes extensive use of plasma (a physical phenomenon) and reactive PVD (evaporation or sputtering) occurs in a chemical environment. Much ofthenew equipment reflects this process integration in the concept of cluster tools which may incorporate CVD, etching, sputtering, and ion implantation in one piece of equipment. 

The Cluster Tool Concept. A recent trend in semiconductor equipment is the integration of two or more functions, such as CVD, PVD, etching, stripping, or rapid thermal processing, in one piece of equipment the so-called cluster tool. A continuous vacuum can be maintained, a feature which reduces the handling and contamination problems, increases the overall throughput, improves the process control, and generally lowers the cost. 

Enhanced ToxSeek Meta-Search Engine and Clustering Tool... 

ToxSeek is an NLM metasearch engine and clustering tool that enables the simultaneous searching of many different toxicology and environmental health information databases and web sites. This tool includes 59 databases including the TOXNET Search tool, as well as information sources from NLM, NIH, US Government, International and other sources. 

Sequence clustering tools Sequence clustering tools are programs that take a large set of sequences and divide them into subsets or clusters, based on the extent of shared sequence identity in a minimum overlap region. 

Equipment CMP tools for microfabrication are not covered by the large equipment manufacturers as it is still regarded as a niche market. Therefore, the supply situation for MEMS CMP tools consists not only of older, used polishers for small wafer sizes but also of specialized, highly M EMS dedicated polishers and cleaners from smaller companies. The bandwidth varies between simple tabletop polishers for R D and fully automated CMP cluster tools for production. As the process requirements are equal to or even exceed those of microelectronics, simple polishers or refurbished older generation CMP equipment often carmot meet the demands of the planarization process for microfabrication. 

With regards to this it is clear that the wafer pretreatment is of key importance for obtaining good selectivity. Such pretreatments can vary from wet clean steps to in situ dry clean steps. In situ clean steps have the advantage that they can be done in vacuo in an integrated (cluster) tool. Unfortunately not much has been published in the literature about the in situ pretreatments. In one study a NF3 plasma is reported to be able to remove native oxide from silicon [Kajiyana et al.84]. 

The post deposition treatment step in case of selective tungsten might be necessary to restore the effects due to selectivity loss or to remove the nail heads formed due to the depth variations of the contacts. We see that the amount of process steps (and the associated yield losses) can well be equal for selective and blanket tungsten. Fortunately, in both cases the three process steps can in principle be integrated in a cluster tool which can improve repeatability (see chapter VII). 

The most important development in the near future is the introduction of cluster tools (see figure 7.13) or "integrated processing". At this moment about 20 cluster tools are available for various types of... 

Figure 7.13. Principle of a cluster tool. Via a central loading station several processing units are integrated. The units can be either single wafer or batch type.

Blanket and selective tungsten plug processes are two of the first candidates for cluster tool integration. In the case of blanket tungsten the necessary process steps are ... 

Fig. 3 Cluster tool ( Endura Classic from Applied Materials, Inc.) for accomplishing metal deposition on 200 mm diameter wafers. The various individual tools for unit operations surround a central handler (lower center) that transfers wafers among them. (Photo courtesy of Applied Materials Inc.) (View this art in color at www.dekker.com.)...

Figure 4-13. (a) Schematic of horizontal tube (b) schematic of cylindrically symmetric vertical barrel reactor tube (c) schematic of circularly symmetric Planetary Reactor (d) schematic of vertical pedestal reactor (pedestal may be rotated or entire reactor may be inverted) and e) schematic of cluster tool type reactor systems. (Courtesy of EMCORE Corp.). 

Figure 4-13e shows a cluster tool configuration. Such configurations are common in Si production lines, but not in compound semiconductors. This type of configuration will continue to gain in importance as compound semiconductors, like Si, try to sequence multiple process steps with minimal exposure of the wafer to impure environments. 

True compound semiconductor production, in the Si sense of production, has only recently begun to come about with the introduction of large planetary systems and cluster tool compatible reactors [18]. Si equipment manufacturers have been reluctant to enter this niche market in force, and are generally unlikely to do so in the near future because of the small market size (—35-50 million dollars compared to the multi-billion dollar Si equipment markets, for example see Applied Materials sales). 

An applet version is also available that can be used on any website with no special server-side setup. ChemAxon provides clustering tools to analyze hundreds and thousands of molecules (Library MCS) via maximum common substmctures... 

Natural and synthetic diamonds have been used for many years to true up and dress abrasive wheels. These are held in a holder of the required shape by vacuum brazing or held in a powder metal matrix and can be single point tools, multi-point grit tools, blade tools or cluster tools depending on the application (see Fig. 10.10). 

Cluster Tools. Many cleanroom processes can be combined into what is termed acluster tool. These are discrete functional modules linked to a central robot that allows the semiconductor device manufacturer to purchase one process tool that may perform dry etching, metallization and passivation in one piece of equipment. By 1995, cluster tools are expected to make up greater than 60% of the semiconductor thin-film processing equipment market. P ]... 

From an IH perspective, cluster tools tend to have concerns comparable to the processes occurring on standard fabrication equipment. One... 

In the last decades, most researchers have used statistical analysis to discover the relationships between circumstances and accident occurrence. Accident circumstances are usually structured as a flow of events (Rajala N yrynen, 2010) and then analyzed with contingency tables. Also, exploratory techniques (Chi Chen, 2003) and clustering tools (Palamara et al., 2011) have been used to identify sequences of events and their prevalence. Finally, correspondence methods have been applied to explore relationships among certain variables, as between deviations and type of injury of the accidents (Conte et al., 2011). 

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