Specific Process Knowledge/Cross Contamination: Difference between revisions
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For example, contaminations during a thermal oxidation process to grow silicon dioxide (SiO₂) layers on silicon wafers can significantly degrade the quality and functionality of the resulting oxide layer. Especially metal ions pose a serious issue as they increase leakage currents, reduced the breakdown voltage, reduce the dielectric strength, and cause threshold voltage shifts in MOS devices. But contaminants can also alter the stoichiometry or uniformity of the oxide layer due to non-uniform growth rates and the formation of defective or porous oxides. Therefore, thermal oxidation furnaces have to be maintained extremely clean and the cannot be cleaned easily. | For example, contaminations during a thermal oxidation process to grow silicon dioxide (SiO₂) layers on silicon wafers can significantly degrade the quality and functionality of the resulting oxide layer. Especially metal ions pose a serious issue as they increase leakage currents, reduced the breakdown voltage, reduce the dielectric strength, and cause threshold voltage shifts in MOS devices. But contaminants can also alter the stoichiometry or uniformity of the oxide layer due to non-uniform growth rates and the formation of defective or porous oxides. Therefore, thermal oxidation furnaces have to be maintained extremely clean and the cannot be cleaned easily. | ||
'''''Please note, as a multiuser facility we need to establish working procedures to provide the best possible working environment for our users, not only in terms of safety, but also regarding reliability of equipment and prcoess run on tose. We expect all users to adhere strictly to the guidelines and equipment usage rules, with particular attention to preventing cross-contamination between tools. We are happy to assist you in reviewing and refining your process flow to help streamline your work and ensure compatibility with our facility standards. You can find more information on how to create a process flow [[LabAdviser/Process flow approval|here.]]''''' | |||
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To evaluate the viability of your process and cross contamination of your sample, you have to consider | |||
* Is your sample with its particular attributes allowed in the tool? ("'''In"''') | |||
* Does the tool contaminate your sample during processing? ("'''Out +"''') | |||
* Does the tool remove a particular attribute from your sample during processing? ('''"Out -"''') | |||
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* These are not legal documents – it is an attempt to preserve our tools in known states. | |||
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Always consider the tool to be working and used correctly by a skilled user where a meaningful process has run to completion. | |||
We expect users | |||
Please note, a processed sample can be coated with more than one film. For some processes, only the top layer may be evaluated with respect to cross contamination, f.ex. if buried layers are not exposed during the process and traces can be disregarded for the process. But for other processes, all layers need to be evaluated, f.ex. if you etch through several layers, you will expose underlying material. In that case, all layers need to be considered for the cross contamination. | Please note, a processed sample can be coated with more than one film. For some processes, only the top layer may be evaluated with respect to cross contamination, f.ex. if buried layers are not exposed during the process and traces can be disregarded for the process. But for other processes, all layers need to be evaluated, f.ex. if you etch through several layers, you will expose underlying material. In that case, all layers need to be considered for the cross contamination. | ||